Manchester United 1-1 Arsenal: Olivier Giroud heads in late to save Gunners' blushes - 5 things we learned

Juan Mata struck in the second half but the French substitute headed in late to deny Jose Mourinho's men all three points at Old Trafford

Jose Mourinho and Arsene Wenger resumed their bitter rivalry, with the Arsenal boss looking to score a first Premier League win over his managerial nemesis.

And it was the Frenchman who had the last laugh with Olivier Giroud snatching a late equaliser their play all afternoon scarcely deserved.

Juan Mata looked to have continued Wenger's dismal run against Mourinho putting the home side ahead after the hour.

But despite never looking likely throughout Giroud popped up in the right place at the right time to save his team's - and his manager's - blushes with a well-taken header.

Here are five things we learned from today's lunchtime kick-off at Old Trafford:

1. Mourinho and Wenger remain civil

Despite the ongoing enmity between them, those expecting fresh touchline fireworks between the the two rival bosses were left disappointed.

There were no flare-ups, no shoving and little in the way of conflict.

The only time the pair did clash was over Alexi Sanchez's booking for clattering into Ander Herrera, Mourinho mouthing off at Wenger as he protested to the fourth official.

2. Carrick allows others to flourish

Mourinho handed Carrick only his second Premier League start of the season, and the veteran midfielder vindicated the decision.

Carrick's calming influence and willingness to screen the defence liberates others, notably United's record signing Paul Pogba, who was able to play in a more advanced role, where he is so much more effective.

3. Valencia return gives United extra dimension

Antonio Valencia made his return from a three-week lay-off ahead of schedule and showed United what they had been missing in his absence.

He rampaged down the right throughout, pushing Nacho Monreal back and giving United an extra attacking thrust.

He should also have had a penalty in the first-half when Monreal put his arm across him after the United right-back had beaten him.

4. Cech proves his enduring class

Mourinho knows all about Petr Cech's qualities from their success together at Chelsea, and the Arsenal goalkeeper reminded his old boss of his enduring class with a series of crucial saves in the first-half.

Cech saved once from Juan Mata and twice from Anthony Martial to keep the Gunners in the game. Despite those heroics, he was powerless to stop Mata's opener.

5. Wenger's substitutions pay off

The Arsenal boss threw on Alex Oxlade-Chamberlain and Olivier Giroud to try to salvage a point and the pair duly delivered, combining for their 89th-minute leveller.

Questions will be asked about United's marking and defensive organisation, as Giroud rose above everyone at the far post to power Oxlade-Chamberlain's cross beyond David De Gea.