Arsenal manager Arsene Wenger said Francis Jeffers fully deserved the red card that cost his side's chances of lifting the Community Shield against Manchester United.
Jeffers became the 50th Arsenal player red-carded under manager Arsene Wenger when he was sent off 19 minutes from time after kicking out at Phil Neville.
But Gunners boss Wenger had no sympathy for the £8m signing, who has been linked with a move away from Highbury.
"The red card was deserved. Francis knows he overreacted and should not have done it," said the Frenchman.
"He's apologised. He realised he made a mistake. He's intelligent, he's young and he'll learn."
Arsenal's ranks could have been further reduced had referee Steve Bennett not shown lenience to Ashley Cole and Sol Campbell, who also showed a lack of restraint.
Wenger said: "We certainly didn't want to go down to 10 men in that heat.
"But while the incident with Jeffers was right in front of me, those involving Ashley Cole and Sol Campbell were over the other side of the pitch."
There was little to separate the giants of English football as they limbered up for the campaign.
Manchester United defender Mikael Silvestre denied that lifting the Community Shield gave his side a psychological edge.
Silvestre said: "This is still a pre-season game. We won the Premiership title with a strong run at the end of last season.
"I don't think this gives anyone an edge."
Silvestre also conceded that Manchester United were still coming to terms with the loss of David Beckham and Juan Sebastian Veron.
The French international said: "It's difficult to not have Becks and Seba around, especially because they were so good at free-kicks and that's something we have to work on.
"But we have made some good signings. Eric Djemba-Djemba came on and did well and we demonstrated today that we're as strong as last season."
Meanwhile, United's penalty shoot-out hero Tim Howard does not know if his feat will earn him the number one jersey at Old Trafford this season.
Howard, a £2.3m summer signing from NY/NJ MetroStars, saved penalties from Giovanni van Bronckhorst and Robert Pires.
The big American's all-round performance was a nudge to United boss Sir Alex Ferguson that he can displace Frenchman Fabien Barthez.
But Howard said: "I don't know whether I will be starting the season, that's not my decision.
"We have four great goalkeepers and we're looking to have a good battle all season long."