Roll up, roll up, it's day four of the World Cup! We've got the defending champions and the boys from Brazil to come, but first, it's Costa Rica v Serbia...

And there's the full-time whistle! Late onslaught from Costa Rica but Serbie survive and get their campaign off to the perfect start.

Once again VAR is checking something...

Prijovic looks to fend off Acosta and actually slaps his face... Looks accidental, but the referee goes over to check it... Just a yellow though.

Offside at the death! We're into added time of added time as Colindres is flagged for offside after firing an attempt over.

Oh no! Serbia go on the counter after a Costa Rica corner, but Kostic gets it all wrong when they have a 4 on 1.

Bizarre moment follows as a Costa Rica staff member takes the ball when it goes out for a throw-in to Serbia. Not quite sure what he's trying but it sparks a wee melee. The referee stops as VAR check for any offences...but eventually the game carries on.

Very ambitious attempt from Gamboa 30 yards out, and Stojkovic gets down to make a simple save and eat up some valuable seconds.

Kostic tries his luck from the edge of the area, but his effort flies over the bar.

FIVE minutes added on - not sure where that came from!

Last change for Mitrovic, who looks away for a while as he pretends he doesn't know his number is up. On comes Prijovic.

Mitrovic goes down in the box under pressure from Gonzalez and it's no penalty... initially. VAR time?? Nope... replays show he fell under minimal contact, and it's not deemed worthy of checking on the sidelines.

Worrying for Costa Rica. The clock is ticking towards 90 and they've had little to shout about this half.

Tadic is off for Serbia, with Rukavina coming on.

Risky defending from Duarte as he attempts a scissor-kick, but he just about gets away with it with Mitrovic breathing down his neck.

Costa Rica reduced to pot-shots from the edge of the area. Campbell sees an effort blocked before another shot is blocked 18 yards out.

OVER! It opens up for Milinkovic-Savic 20 yards out, but he rushes the shot and fires it high and wide of Navas' goal.

CHANCE! Tadic's cross evades Navas, and it somewhat surprises Kostic inside the six-yard box as it ricochets off his shin and away from goal. Gets it all wrong as he looked to turn it in... Replays show Navas gets a vital touch onto it to put Kostic off!

Campbell gets behind Milenkovic, but the Serbia defender turns and chases down the forward to put it out for a corner, which comes to nothing for the Ticos.

Guzman off, Colindres on - their final sub, and that's an attacking switch.

Costa Rica enjoying more of the ball as they look to take the game to Serbia, but on this occasion a Campbell free-kick is headed clear.

And it's a like-for-like sub from Serbia too, with Kostic replacing Ljajic for their first change.

Slight surprise to see Urena go off with Costa Rica pushinhg for the equaliser. Not really the time for like-for-like subs, particuarly with Campbell dropping deep to pick up the ball on occasion.

WIDE! Good cross from Ivanovic picks out Milinkovic-Savic, but he can't direct his header on goal.

Meanwhile, Costa Rica make a second sub, with Joel Campbell coming on.

Serbia remain on top and will look to extend their one-goal advantage.... You feel if Costa Rica want to repeat their 2014 heroics then they have to take something from this game.