The referee spots some shenanigans in the box as Chelsea take a corner. They get another crack at the corner but it's headed away by Moussa Marega.

Good defending by Cesar Azpilicueta to track Luis Diaz's run in behind and stop the Porto striker.

A scare for Chelsea but they escape. Moussa Marega gets in behind their defence and Edouard Mendy has raced off his line a bit needlessly. Luckily for the 'visitors' Mendy recovers to save Marega's shot from a tight angle.

Corona nutmegs Ben Chilwell and then goes to ground hoping to win a free-kick because he can't get the ball on the other side. Nope.

Right, let's see what the second half in this one has for us.

We're back under way, although not before there is another substitution as Mitchel Bakker comes on for Abdou Diallo.

Clinton Morrison
Former Republic of Ireland striker on BBC Radio 5 Live

Timo Werner has to score! The football from Chelsea was brilliant, back to front to beat Porto's press. It's a header from a striker that is not confident.

Chelsea have their first chance of the game that isn't a goal. Mason Mount whips in a nice cross from the right which Timo Werner heads over the bar.

Back under way in Seville.

PSG are aiming to become the first team to win a European away match against both Bayern and Barcelona in a single season.

This is the first Champions League knockout phase match to feature more than two substitutions in the first half.

Clinton Morrison
Former Republic of Ireland striker on BBC Radio 5 Live

Image source, Getty Images

It's been a good first half. Porto have done well. Mateus Uribe has been finding good pockets of space and they look threatening on set-pieces, but Chelsea have defended really well so far and have dominated possession.

Only took half a chance for Mason Mount to make the goal for himself. He hasn't really been in the game but it only took one chance for him. Big players turn up for big games and at that point, Mount turned up.

This game isn't over, though, as Porto are still dangerous on the counter-attack.

The whistle goes for half time.

If the second half can deliver as much entertainment as the opening 45 minutes has then we will be in for a treat.

Two minutes of time added on at the end of what has been a brilliantly entertaining first half of Champions League football.

There's a late chance for Bayern but Thomas Muller's header from a corner lacks power and Keylor Navas holds comfortably.

Mason Mount has scored more goals under Thomas Tuchel than any other Chelsea player (5).

JS: Havertz looking completely lost again tonight.

Alan: Kane to PSG anyone? I think he'd be mad not to go if Poch came a calling.

The half-time whistle goes. So far, so good for Chelsea.

Lovely play by Porto's Mateus Uribe. He gets the ball, spins and beats a couple of Chelsea defenders and has a shot blocked for a corner.

From the corner Marko Grujic heads it at the keeper.

A second substitution for Bayern Munich as Niklas Sule is replaced by Jerome Boateng.

Three goals and three substitutions in this game before half time.

From the corner, Pepe - the sweetest man in the world apparently - gets a decent header onto it which Edouard Mendy dives to keep out of his goal.