In answer to your question Colin, the record is a whopping 12 yellow cards.

That was in both the Real Madrid v Atletico Champions League final in 2014 and Bayern Munich v Juventus in March 2016.

There's no second booking for Ashley Young.

Postpublished at 40 mins

40 mins

Man Utd 0-0 PSG

Oooofff! Angel di Maria is helped off the pitch by Ashley Young, there's a big drop-off at Old Trafford as you'll know and the Argentine absolutely batters into the boards down there.

Ouch!

All manner of folk get involved in a bit of pushing and shoving, with Young getting a classic finger wag in the face from Thiago Silva.

Image source, AFP

Almost the breakthrough! Edin Dzeko has a shot saved on to the post by Iker Casillas.

Still got it...

Angel di Maria's blushes are saved by an offside flag - he runs through, goes around David de Gea and then totally duffs his shot. De Gea makes the save.

Anthony Martial is now down getting some treatment. And Colin, we are asking about that...

Image source, Reuters

Colin Bundred: What is the record for the most yellow cards given out in a CL game? Whatever it is this ref's trying to beat it...

Edin Dzeko has just put a header over in Rome. Not much else has happened in the first half.

PSG come away down their right, lovely one-touch stuff stretches the play and Marco Verratti could play in Angel di Maria but puts too much on his pass and it skims out of play.

Almost. Signs of their talent.

Image source, Reuters

Presnel Kimpembe, one of the four men already on a booking, is late on Luke Shaw. Referee Daniele Orsato does not show a second yellow but he has given himself a bit of a problem here, the ref.

There's another one! Juan Bernat is late on Ashley Young and he goes right into the book!

Image source, PA

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You can rate the players until 30 minutes after full-time - head over here to give it a go.

Nicks: I know I’m talking too soon but it would be an incredible feat if this Man Utd team went all the way in Champions League. OGS could do what Roberto Di Matteo did for Chelsea

Aamer Iqbal: Martial very quiet. Will probably score a Worldy ... fingers crossed.

Simon Stone
BBC Sport at Old Trafford

Ryan Giggs, David Beckham and Nicky Butt are all sitting in the directors' box, while Phil Neville commentates for Radio 5 Live.

I am not too sure where Gary Neville is but I doubt very much he is at Boundary Park to watch Paul Scholes take his first tentative steps in management.

It's 0-0 there too.

Phil McNulty
BBC Sport chief football writer at Old Trafford

Close. Very close. The noise levels from the PSG fans rose as Kylian Mbappe got on the end of that chance only to turn it wide.

Mbappe's pace already causing problems - then again it would cause problems to any team in the world.

Going to be a lot of sore throats among these PSG fans. They have not stopped chanting all night.

Image source, Reuters

End to end now! Luke Shaw has a cross blocked and PSG break with intent, Ashley Young has a hand on the back of Kylian Mbappe and that's a booking.

These yellow cards are mounting up.

Phil Neville
Ex-Man Utd and England defender on BBC Radio 5 live

Mbappe was put off by David de Gea, he just peeled off the back of his defender. It was a lovely pass from Julian Draxler.

De Gea was so quick off his line.

Manchester United need to lift the tempo, PSG are happy to slow it down.

Image source, Reuters

Close! Almost the opener for PSG, and it's lovely football. Lovely.

They pick the passing around the edge of the area, methodical, Marco Verratti then feeds one into Julian Draxler in the D, he knocks it first time into the run of Kylian Mbappe, he has a shot from a tight angle and it's into the side netting.

Very close!

Image source, Getty Images

Careful now, Dermot...

Image source, Getty Images

Jay Barnes: It's mind boggling how just a couple of months ago, Dermot from Lisburn would probably have preferred watching the paint on his ceiling dry

Allan Done: Hope Dermot doesn't fall off his ladder if there's a goal

Referee Daniele Orsato isn't here to make any friends, he now books Paul Pogba for a nibble on Marco Verratti. Soft.

As my brother would say, not every foul has to be a yellow ref...

Phil Neville
Ex-Man Utd and England defender on BBC Radio 5 live

That was a really good counter-attack, really good link-up play by Manchester United.

The gates were open but Jesse Lingard just played the ball that little bit too far behind Anthony Martial.

Image source, PA