Arsene Wenger believes Arsenal midfielder Jack Wilshere feared he may never play again during his long struggle to return from a series of injuries.
Wilshere was back in full training this week for the first time since before the start of last season following a frustrating 14-month rehabilitation from ankle and knee problems.
The 20-year-old was sidelined for so long that Arsenal boss Wenger admits there were times when the England international was at a low ebb and would begin to doubt his ability to make a complete recovery.
"When you are so young and out for 14 months that is a good test for your mental strength," Wenger said on Friday.
"Jack had ups and downs, and many downs because he had a few setbacks, but he dealt with it very well, especially in the last three months he was highly focused every day.
"I refused to give up, because he is a 19-year-old boy, so I always thought he would come back.
"I am not medically expert enough to know how big the damage was in his ankle. It never crossed my mind. Has it crossed his mind? Only he can answer that -- I think, yes."
While Wilshere struggled to remain positive at times, Wenger said he had been impressed with the way the midfielder always bounced back eventually -- and he is confident that determined streak will hold him in good stead once he plays again.
"He has been absolutely brilliant because he had not only ankle surgery but when he thought that was over he had knee surgery. He handled that very well, I must say," Wenger said.
"Jack, though, has always been with a good level of confidence. I believe what he has gone through will make him even stronger. He was in every day very early and worked all day through. He is rewarded now with a good condition."
Wenger has no intention of ruining Wilshere's comeback by rushing him into the first-team and he will be reintegrated slowly, with a run-out for the reserves likely in 10 days' time.
"We will see how he responds to the training now," said Wenger, who takes his side to Premier League champions Manchester City on Sunday.
"We will have to be a bit patient, a bit cautious, because when a guy has been out or 14 months it takes a while to get back to match fitness.
"Jack is fit to practice and play but to put high-level performances in takes time. He will need a few games in the reserves."