Emile Smith-Rowe and Martin Odegaard are starting to come into the game, which is good news for Arsenal. The latter tees Thomas Partey up for a speculative effort from distance that finds the cardboard cutout fans in the stands.

Pau Lopez looks like he wants to play on as he swings his shoulder round - moments after the physios seemed to hold it in place. Was it dislocated? Strange.

Either way, Roma bring on their 37-year-old second-choice keeper Antonio Mirante.

That's two forced injuries for Roma in half an hour.

No surprise that it is Bukayo Saka with Arsenal's first attempt on goal after another swift break, cutting on to his left from the edge of the box and curling a strike over the top of the crossbar.

Better from the Gunners.

Richard: If that handball happened in the Roma box and we didn't get a penalty, I'd be fuming. It was clear as day, for me.

Dizz: Pogba slides in with his arms above his head and blocks a cross thats well above his body. I don't see how you can really argue that...

Image source, Getty Images

Pau Lopez has hurt himself. Seconds after that save he screamed, held his shoulder and collapsed.

They're getting a sub keeper ready.

A positive spell from Manchester United and Paul Pogba forces a good save from Pau Lopez with a curling effort from outside the box. Aaron Wan-Bissaka has a shot blocked with the rebound.

Chance for the hosts to deliver now from a corner but it's well cleared by Arsenal and suddenly the break is on for Mikel Arteta's side. Dani Ceballos can see Nicolas Pepe out of the corner of his eye but can't quite find the pass and Gerónimo Rulli comes rushing out to intercept.

People are free to disagree with the handball laws but it's quite clear that if your arms are in the air and the ball hits them it's a penalty.

By the new laws it was definitely a penalty.

Bruno Fernandes steps up to take it but he curls both high and wide. Well below his usual standards.

Maybe he should have done the Riyad Mahrez and just shot at the wall.

United win a free-kick in a good position as Roger Ibanez jumps all over Marcus Rashford needlessly.

Villarreal haven't really threatened since the opener, but then neither have Arsenal. The goal remains the only shot in the game so far, and we've hit the 20-minute mark.

Now Aaron Wan-Bissaka is penalised for handball, luckily at the other end of the pitch as he slides on the ground and takes the ball with him with his arm.

Good footwork again from Bukayo Saka but his curling delivery is nodded away comfortably. Arsenal playing without a recognised centre forward in Spain...

Four of the last six penalties Manchester United have conceded at Old Trafford have been given away by Paul Pogba.

Image source, Getty Images

Bruno Fernandes has scored 25 goals this season. The only two Premier League players to net more in all competitions are Harry Kane (31) and Mohamed Salah (29).

Simon Stone
BBC Sport at Old Trafford

Hero to zero for Paul Pogba.

A superb involvement in Manchester United's opener - an unfortunate one in the equaliser.

Can't keep him out of the action.

Deliberate handball hasn't been the rule for a couple of years now.

The Turbo Bear: What on earth is Pogba supposed to do with his hands here? How is that a penalty? Give us our game back!

Dawesy: VAR has killed this game. How is that ever a deliberate handball?? He’s two foot away and sliding. Absolute rubbish

Iain Moss: Footballers should just cut their arms off. This is getting absolutely ridiculous. Where's pogba's arms supposed to go? The goal celebration slide shows how your arms naturally go up when you slide!!!

Better from Arsenal as Bukayo Saka cuts inside and switches play out to Nicolas Pepe, but Juan Foyth covers well and tidies up for the hosts. Calum Chambers is then called on to make a last-ditch tackle of his own at the other end as Villarreal come flooding forward.

Pepe gets Foyth one-on-one again moments later but his cross is blocked. It's suddenly become end to end.

Two shots, two goals.