Lyon scout Gerard Bonneau has revealed that now Atletico Madrid attacker Antoine Griezmann slipped through the club's net when the Frenchman was a youth.
Bonneau has said that the France international trained with Lyon "every Wednesday" during his younger years, but he was ultimately overlooked by the French outfit due to the fierce competition in the youth team.
Griezmann instead joined the Real Sociedad academy in 2005, progressing through the youth set-up before going on to make almost 200 league appearances for the Spanish club.
"It was our biggest mistake in years, a historic mistake. We had him every Wednesday but didn't make a move. In the end, Real Sociedad signed him two years later," Bonneau told AS.
"He wasn't let go because of his small stature. We don't only look to keep the physical players. The truth is that in his generation and in position, we had three players who also had a lot of promise.
"They were [Alexandre] Lacazette, [Clement] Grenier [both of whom are in Lyon's first team] and [Yannis] Tafer [now with Swiss side St Gallen]. He was let go and it was a shame."
Griezmann, who is now thought to be worth upwards of £40m, joined Atletico in the summer of 2014 and has scored 32 times in 69 games for the former Spanish champions.
