Called into action early on when Van Persie picked Arteta's pocket but even he looked shocked at how easily he saved the Dutchman's effort. Then rose to the challenge with a superb save from Van Persie's late header.
Put Saturday's miserable performance at Anfield behind him with a sturdy performance here, brilliantly denying Van Persie early in second half with the Dutchman about to shoot. Almost nodded a second-half winner, too.
Save to two efforts thwarted by Szczesny, Van Persie had a night to forget and that was in no small part down to the towering presence of Mertesacker who nullified his former captain's threat all night long.
Delivered pin-point crosses from his right-back position all night but was continually let down by the finishing in the middle. Arsenal must convince him to sign a new deal at the club.
Arsene Wenger gave Gibbs the nod over Monreal and he repaid his manager's faith. Looked strong in attack and defence all night, dealing well with Valencia and also providing ammunition for Giroud.
Arguably Arsenal's best midfielder on the night, driving play through the centre. He received some criticism for some early-season performances but he seems to have put all that behind him.
Ran around a lot and used the ball well but struggled to find the killer pass. Almost got lucky in the first half with a dipping, long-range effort which took a wicked deflection but De Gea managed to hold on to it.
Not bad from the German, especially considering some of the criticism he has taken this week, but Arsene Wenger might have hoped for more after admitting he wanted a "reaction" from his £42m star.
Not the Spaniard's best night's work and almost gifted Manchester United an early opener when he dallied on the ball, allowing Van Persie a clear run at goal. Regrouped after that but did give it away a few more times.
Probably Arsenal's biggest attacking threat, looking dangerous with both feet whether shooting himself or teeing up Giroud. Can be happy with his contribution.
It's never easy playing up front on your own but this looked particularly difficult. Spent half the night flicking the ball on to no one and the other half wandering back from offside positions.
Very little to do all night but was beaten all ends up from Laurent Koscielny's header – although Antonio Valencia managed to clear it off the line. He also saved well from a long-range Santi Cazorla effort in the second half.
A decent first-half performance at centre-back from Smalling and looked OK at right-back once Rafael had been replaced, although he leaves a little to be desired on the front foot.
Had to work hard to contain the marauding Kieran Gibbs, who worked hard to get up and down in the first half. But the little Brazilian had to come off at half-time after landing on his neck following an aerial tussle with Olivier Giroud.
A good performance from the United left-back, who looked to push forward and offer something in attack whenever possible. Rarely caught out defensively, either.
Can be pleased with his performance alongside Smalling then Ferdinand although he was a little lucky not to concede a penalty when he bundled Olivier Giroud over in the second half.
Like Carrick, didn't really put a foot wrong in possession but he did not offer enough going forward which left United's front three too isolated. He should be dominating games like this.
Fairly lively down the right flank without ever really producing his best – or getting to the byline and crossing the ball. His most telling contribution came at the other end when he cleared Laurent Koscielny's second-half header off the line.
A quietish evening for Carrick, although it often looks like that for the composed midfielder. Plenty of neat and tidy passing but he often lacked incision.
Should have thrived in the hole for United but was well marshalled by Arsenal's deep-lying midfielders. Almost set up the winner with a sublime cross for Robin van Persie but his strike partner's header was tipped onto the bar.
So much was expected of Juan Mata after his switch from Chelsea in January but, on this evidence alone, he will need some time to bed in. Nothing he tried came off and he looked a little lost going forward and backwards.
R. van Persie
Low rating comes as a result of early miss alone. Should have scored within two minutes of the start but froze and shot tamely straight at Szczesny. Almost made amends with a late header but the keeper tipped it onto the bar.
Good, strong performance from the half-time substitute and won the battle with Olivier Giroud in the second half. Also looked typically assured whenever in possession.
Not enough time to influence the game and rarely found a way past the full-back.
Might have hoped to start here given his performance off the bench against Fulham but struggled to make an impression with his 15 minutes on the pitch.