France come into this match looking to reach a third World Cup final in the past 20 years following victories over Argentina and Uruguay in the knockout stages so far.
Belgium, meanwhile, are bidding to reach the final for the first time in their history and are already guaranteed at least their joint-best ever finish having won every match in Russia so far.
Make sure you don't miss a moment of the action courtesy of our minute-by-minute coverage below.
FRANCE: Lloris; Pavard, Varane, Umtiti, L Hernandez; Pogba, Kante, Matuidi; Mbappe, Giroud, Griezmann
BELGIUM: Courtois; Alderweireld, Kompany, Vertonghen; Chadli, Witsel, Fellaini, Dembele; De Bruyne, Lukaku, E Hazard
What a performance from France that is - full of attacking flair from Mbappe and defensive solidity. Neither team played badly tonight and Belgium can feel themselves a touch unlucky to crash out here consider how impressive they have been in this tournament.
Football matches at this level are determined by the narrowest of margins, though, and in the end Umtiti's header was the difference. France are in their third World Cup final in the past 20 years, whereas Belgium will face either Croatia or England in the third-placed playoff. Thaks for joining our live coverage of the match!
90+7 min FRANCE ARE IN THE FINAL OF THE 2018 WORLD CUP!
90+7 min FULL TIME: France 1-0 Belgium
90+6 min CHANCE! Another big chance for France to kill this game off once and for all. The ball is worked to Tolisso in space and he really should score, but Courtois makes another good save.
90+4 min YELLOW CARD! Again the ref goes to his book, this time to show Vertonghen a yellow for a foul on Mbappe.
90+3 min CHANCE! Chance for France to put this game to bed as the ball is laid into the path of Griezmann, whose finish is a tired one and is easy for Courtois.
90+2 min YELLOW CARD! Mbappe now goes into the book for dribbling the ball away when Belgium were trying to get it back.
90+1 min BELGIUM SUB: One last throw of the dice for Belgium as Chadli is replaced by Michy Batshuayi.
90+1 min There will be SIX minutes of added time at the end of this match! Still time for Belgium!
89 min The initial free kick is eventually scrambled clear by France but De Bruyne soon has the ball at his feet again and this time he pings a pass over the top which is inches away from the head of Lukaku.
87 min YELLOW CARD! Kante goes into the book for a foul on Hazard, who was always the wrong side of his Chelsea teammate.
86 min FRANCE SUB: Matuidi is still feeling the effects of that Hazard collision and he makes way here to be replaced by Corentin Tolisso.
85 min FRANCE SUB: France make their first change of the match as Steven N'Zonzi replaces Giroud. I suspect there will be a couple more coming to run that clock down.
83 min Moments after that save there was a heavy collision between Hazard and Matuidi, the latter of whom is still down and needing treatment. He bore the brunt of that one from Hazard, who left a little on him.
81 min SAVE! Hazard again embarks on a run but this time Varane dives in with a perfectly-timed challenge. The ball comes out to Witsel who drives a ferocious effort towards goal which Lloris needs to parry away.
80 min BELGIUM SUB: Another change for Belgium sees Yannick Carrasco replace Fellaini.
80 min Really good play from Hazard as he darts into the box and almost draws a foul before being pushed out of the area. He is then felled by his Chelsea teammate Giroud, but somehow the referee does not give a free kick right on the edge.
78 min A second for France now would surely kill this game off, but Belgium have to throw caution to the wind. They know that France have the ability to hurt them on the break, but they simply have to start taking risks now.
76 min SHOT! De Bruyne picks the ball up in a bit of space just outside the area, but he is quickly closed down and his eventual effort is wild and flies over the crossbar.
75 min Here is that incredible piece of skill from Mbappe which created a chance for Giroud. The man is only 19 years old, and he is doing this in a World Cup semi-final!
73 min Just over 15 minutes remaining in this World Cup semi-final now and Belgium are really beginning to run out of time now. Their pressure has begun to grow in the last five minutes or so and France are dropping increasingly deep, but those seconds are ticking away.
71 min YELLOW CARD! Alderweireld goes into the book for a cynical challenge on Matuidi.
67 min Mbappe is really enjoying himself here. He skips away from De Bruyne and then clips a pass over to Griezmann, whose control is instant. He plays the ball back into the path of Giroud, who fires the ball well over the crossbar.
65 min CHANCE! Mertens has made an impact already here, and he swings a good cross into the box which Fellaini meets with a powerful downward header which bounces just wide of the target.
63 min YELLOW CARD! Hazard is the first name in the book tonight for a cynical challenge on Matuidi following a rare mistake from De Bruyne.
61 min Almost a chance for Belgium as Mertens is immediately involved, getting to the byline and standing a cross into the middle. The ball is only cleared as far as De Bruyne, but he scuffs his volley into the arms of Lloris.
60 min BELGIUM SUB: The first change of the night unsurprisingly comes from Belgium as Dries Mertens replaces Dembele.
58 min Mbappe really is something special, and at just 19 years old he is only going to get better too. Real Madrid must be opening their cheque books following today's news of Ronaldo's exit as Hazard and Mbappe have been brilliant tonight.
56 min CHANCE! Another devastating break for France sees them break forward through Mbappe down the right, and he plays the ball across for Matuidi. Matuidi's effort is blocked, but France keeps the pressure on and Mbappe then produces the most impudent of flicks to send the ball into the path of Giroud, who is thwarted inside the area.
53 min That is a huge, huge goal for France. Belgium now have no option but to throw more caution to the wind, and that could well suit France with the pace of Mbappe.
51 min First blood to France! It doesn't come from a counter-attack, but from a corner as Samuel Umtiti darts to the front post before glancing a header past Courtois at the near post!
The Barcelona man gets above Fellaini - which is no mean feat itself - and the final touch may well come off the Manchester United man. No doubt that Umtiti will be claiming it, though!
51 min GOAL! France 1-0 Belgium (Samuel Umtiti)
50 min Belgium have made a positive start to this second half, but such is the delicate nature of this game that France can break quickly and hit them on the break in the blink of an eye.
48 min CHANCE! He has a very quiet first half, but Lukaku has already been involved more in this second half. Witsel swings a cross into the box and Lukaku gets there ahead of Varane, but he cannot keep his header down.
46 min KICKOFF: Belgium get us back underway for the second half in Saint Petersburg!
The first half comes to an end in Saint Petersburg, and what an engrossing first half it has been!
We remain goalless between France and Belgium, but the quality has been really high and the game is balanced on a knife edge here. both teams have shown that they have the ability to hurt the other in the blink of an eye, and we should be in for a brilliant second half!
45+1 min HALF TIME: France 0-0 Belgium
45+1 min CHANCE! De Bruyne whips another fine ball into the box which Umtiti misses, and Lukaku cannot react in time as the ball hits him and goes behind for a goal kick.
45+1 min There will be one minutes of added time at the end of this first half.
44 min It is a big old Belgian wall separating Griezmann from the goal, though, and he fires his free kick right into the middle of it.
43 min Hazard looks to embark on another darting run, but this time he is dispossessed by Kante and France launch an attack which ends with them winning a free kick in a very dangerous position...
41 min Big save from Courtois there, but still not quite the save of the game so far. That accolade belongs to Hugo Lloris...
39 min CHANCE! Another big chance for France, who should be ahead now! Mbappe pokes the ball into the path of Pavard, who finds himself with only Courtois to beat, but the Belgian keeper spreads himself and makes a crucial save. It is a good stop, but Pavard really should have scored.
37 min SHOT! Some lovely football from France sees them break out and launch a counter-attack, with Griezmann leading the charge. He turns down the chance to pass to Mbappe or Giroud and eventually goes for goal himself, dragging his effort wide of the target.
36 min Less than 10 minutes remaining in this first half now, and it is one which will only whet the appetite further for the second half. It has been full of quality.
34 min CHANCE! Big chance for France! France win the ball back in a dangerous area and Griezmann immediately lifts it over to Mbappe on the right. The PSG cushions a perfect pass into the path of Giroud, but he is a little slow to react to the situation and makes a complete mess of his finish.
33 min SHOT! Griezmann picks the ball up in space outside the area, but he is forced to cut inside onto his weaker right foot and subsequently scoops his effort high over the crossbar.
32 min Hazard has just produced a dazzling run down the left which saw some incredible close control before eventually running out of pitch. He is almost unstoppable when in this form.
31 min CHANCE! Griezmann plays a free kick short to Pavard to improve the angle of any cross, and while Pavard's delivery is poor, Giroud manages to make something of it. His backward header almost drifts in, but Courtois watches it all the way wide.
30 min Vertonghen gets a stern talking-to for a late challenge on Mbappe, who was on his way after flicking the ball off. That was a naughty one by the Tottenham man.
28 min De Bruyne earns a yard down the left flank before playing a dangerous low cross into the box which Umtiti does really well to deal with with Lukaku lurking.
27 min This game has flown by so far. We may still be goalless, but there is so much talent on both sides that it is a joy to watch.
25 min This game is heating up very nicely indeed. Belgium have been on top for the most part, but both teams have spent spells in the ascendency and now it is France's turn to be on top.
23 min CHANCE! Half a chance for France in response here as Umtiti pings a beauty of a ball over the top of the defence for Giroud, who manages to get a toe to the ball but cannot steer it on target. It would have been a stunning effort if he managed to make anything of that.
22 min SAVE! Lloris has made a couple of stunning saves in this tournament, and this is right up there! A corner into the box drops to the feet of Alderweireld, who manages to dig a shot out and wrap his foot around the ball. Lloris is at full stretch, though, and manages to get his fingertips to the ball to deny his Tottenham teammate. Incredible save!
20 min Belgium come forward again here and a cross into the box from De Bruyne almost finds Fellaini, but Lloris comes flying out of his goal to punch the ball clear.
19 min CLOSE! My word, this is close to the opening goal of the game! Hazard looks like he has the beating of Pavard tonight and he dips inside, bursting past the full-back before curling one towards goal. It is certainly goalbound, but Varane manages to get a crucial head to the ball while wrestling with Fellaini to flick it just over the crossbar!
18 min SAVE! France respond with the first shot on target of the match! The ball comes out to Matuidi around 25 yards from goal and he powers an effort towards goal, but it is easy enough for Courtois to deal with.
16 min SHOT! The first effort of the game comes from Belgium as France give the ball away carelessly. De Bruyne is immediately in there and pokes the ball to Hazard, who drills a low strike a yard or so wide of the far post.
15 min This time it is almost Belgium's chance to break as De Bruyne drives forward through midfield, but he and Lukaku are not on the same page. Lots of very encouraging half-breaks, though.
13 min Almost an incredible break from France as they win the ball back and Pogba glides past Dembele. His ball through towards Mbappe looks too heavy, but that pace of his almost sees him reach it. Courtois is alert to gather, though.
11 min France respond as Pogba wins the ball back in a good position and clips an aerial cross into the box. Mbappe watches it over his shoulder and tries to divert it inside, but it is behind Giroud and Vertonghen is able to hack it away.
9 min Belgium are dominating possession at the moment, with France pinned back into their own half. This has been a very ominous start from the Belgians, and some of their key players look in the mood tonight.
7 min A sharp dart down the left sees Hazard ghost past Pavard before playing the ball into the box, but Umtiti is there to knock it behind for a corner. Chadli comes across to take it, but he overhits it badly and it goes out for a goal kick.
6 min The opening five minutes or so have only served to in crease the intrigue of the game. France started on top, but Belgium have just begun to take control of the contest and are putting a bit of pressure on the French defence now.
4 min That said, Chadli has just got forward a couple of times and had a couple of changes to swing the ball into the box. The second sees the ball cleared as far as De Bruyne, who whips a trademark wicked delivery into the box which is just too far ahead of Fellaini.
3 min There was a lot of talk regarding Belgium's tactics tonight, and it looks as though Chadli will be playing as an orthodox right-back, rather than a wing-back. Interesting test for the West Brom player, who is not used to playing so deep.
1 min With barely 10 seconds on the clock Mbappe gives the first glimpse of his lightning pace down the right before playing a low ball into the box which Griezmann cannot latch on to.
1 min KICKOFF: Here we go! The first World Cup semi-final of 2018 gets underway with Antoine Griezmann kicking us off!