Matthew Upson
Former England defender on BBC Radio 5 Live

Image source, Reuters

There is contact, the tiniest contact on the shirt.

Pepe is trying to get his body in between himself and Havertz so to protect the ball in front of his keeper, and the Arsenal forward has a bit of shirt.

I think the referee has saved Pepe's blushes there, there wasn't that much contact in my opinion.

Alex Howell
BBC Sport at Emirates Stadium

Massive decision from the referee. Odegaard has the ball in the net but a foul is given against Havertz in the build up to it. The Arsenal players can't believe it. Arteta is now shown a yellow card!

Image source, Getty Images

Martin Odegaard is off celebrating in the corner as Arsenal think they have taken the lead.

Kai Havertz and Pepe are battling for the ball, the goalkeeper comes out and Porto's captain is pulled back by the Arsenal striker.

It breaks for Odegaard, he dinks it into an empty net but it's ruled out. Replays suggest it's a correct call but Mikel Arteta isn't happy and he's shown a yellow card.

Wendell tugs back Bukayo Saka and the home fans want a free-kick. Play is allowed to go on and Galeno is then brought down by Saka.

The frustration inside the Emirates is increasing...

Alex Howell
BBC Sport at Emirates Stadium

It does feel like the game is on the cusp of opening up. Both sides have had half chances to make something happen.

Image source, Getty Images

Terrible.

Francisco Conceição blasts one miles over the bar. Wasn't even close.

Worse effort than my editor at five-a-side. (He's hopefully reading this...)

Midfielder Pepe breaks through for Porto as they take a quick free-kick, taking advantage of a switch-off from Jorginho.

Gelano heads towards the box and is brought down, bringing another free-kick for Porto just outside Arsenal's area and in a good position.

Matthew Upson
Former England defender on BBC Radio 5 Live

Image source, Reuters

I think this game will quickly boil down to how well Porto deal with these Arsenal set pieces, how concentrated and organised they continue to be.

Arsenal are so good at them this season, it could even end up being a factor in the title race.

Declan Rice's delivery is on the money every time.

Ex-Southampton and Chelsea midfielder Oriol Romeu comes on for Barcelona in an attempt to stop the wave of Napoli attacks.

Sergi Roberto is also on, with goalscorer Fermin Lopez and Andreas Christensen coming off.

Image source, Getty Images

The ball nearly bounces to the feet of Napoli's Victor Osimhen after Barcelona's Ilkay Gundogan cut out a cross, but Marc-Andre ter Stegen was alert enough to dive in front of Osimhen.

Goalkeeper Diogo Costa does well under pressure to punch Declan Rice's in-swinging corner away.

There's a quick VAR check for a potential penalty for a high boot as Bukayo Saka goes for the rebound but it lasts a matter of seconds and comes to nothing.

Ooh. A few deliveries from Declan Rice are cleared by Porto. Arsenal keep the pressure on and Kai Havertz pulls it back to Rice. His strike is blocked by the keeper but it's another corner a few seconds later.

Goalkeeper Diogo Costa kicks it straight at Kai Havertz but Declan Rice can't quite bring it under control when it bounces to him.

Martin Odegaard does well soon after to win a corner.

Napoli's Matteo Politano swings in a free-kick left-footed from close to the right touchline and it causes Marc-Andre ter Stegen some problems. He pats the ball down just underneath the crossbar, but no Napoli players are alert enough to be able to convert the rebound.

At the other end, Raphinha shoots at Alex Meret, who dives backwards to parry it and he does enough.

Image source, Reuters

Matthew Upson
Former England defender on BBC Radio 5 Live

This game could go the full distance here for sure, extra time and possibly penalties.

Image source, Reuters

Jorginho loses possession for Arsenal. Porto break, Jakub Kiwior wins it back and Leandro Trossard is then fouled.

Napoli's Victor Osimhen twice falls to ground in the penalty area, but twice the officials think he has over-egged it and not give him the spot kick he wants.

Image source, Reuters

Jorginho tries to flick it over the top for Leandro Trossard but he's got too much on it and it bounces out for a goal kick.