Former AFC Wimbledon boss Wally Downes has recalled working with Arsenal goalkeeper Aaron Ramsdale.
The 20-year-old, who was on loan from Bournemouth, made a strong impression on the League One club.
Downes told the Daily Mail: "He instilled belief and purpose and he's done the same at Arsenal.
"He's transformed their season because he's engaged the rest of the defence. He makes a great save and they're high-fiving him and fist-bumping, proud not to let a goal in. I've not seen that in an Arsenal team for donkey's years.
"It was a stroke of managerial genius by Mikel Arteta because the season was getting away from Arsenal and the players they were relying on were letting them down. They had a team of young kids and bad role models.
"What they needed was someone with backbone who would not stand for it if others turned up late and did not put their bodies on the line. The kid is not afraid to do that. He's a positive voice, very inclusive, and others feed off him.
"Maybe Arteta saw what he was like, put him in, and he's changed the chemistry of the place."