Mikel Arteta believes that David Raya's save to deny Ollie Watkins changed the momentum during Arsenal's 2-0 victory over Aston Villa on Saturday.
The Gunners maintained their winning start to the Premier League season through second-half strikes from substitute Leandro Trossard and Thomas Partey at Villa Park.
But the encounter could have taken on a different complexion had it not been for a crucial intervention from Arsenal's goalkeeper eight minutes after the interval.
Amadou Onana saw his deflected effort come back off the crossbar and into the path of Watkins, who looked certain to get his tally up and running for the campaign.
However, Raya produced a remarkable instinctive save to deny the Villa striker, who had spurned another golden opportunity in the opening 45 minutes.
"We had to change momentum, we had a 10-minute gap when we didn't get the rhythm, and they were on top," Arteta told Sky Sports.
"They had the big chance and David made an unbelievable save, and it was the magic moment of the game.
"We conceded really little, and it's a big credit to the team as it is a difficult place to come, but when we needed him he was there, and he made a terrific save."
Arteta was also full of praise for Trossard, who emerged from the bench to net the game's opening goal just 110 seconds after being introduced.
The Belgian produced a fine finish from the edge of the area after good work from Bukayo Saka, placing a low right-footed effort beyond the grasp of Emiliano Martinez.
It was Trossard's 14th goal for the club and his sixth as a substitute, while he also registered the most shots (three) of any Arsenal player in his 25-minute cameo.
"The competition is big, we have great players in each position, and they are going to have to accept that," Arteta said.
"We have a huge season in front of us, a long one, and you need players to impact.
"He did that last year when he started and when he was a sub, and he has given us a headache for next weekend."