Chelsea boss Mauricio Pochettino has been playing crossbar challenge with Mykhailo Mudryk to try and improve the winger's confidence.
Mudryk joined from Shakhtar Donetsk in a deal worth up to £89m in January but has failed to score in 22 appearances.
Pochettino and Mudryk have been going head-to-head at Cobham.
"With Mudryk, I like to play sometimes to [hit] the crossbar from outside the box," Pochettino said.
"He said to me, 'I don't want to play anymore with you because you always win.' I said 'yes, because I have the belief, and the balance between belief and quality I know very well because I'm 50 years old. You're still young and you need to know yourself'.
"Today [Tuesday] was the first day we draw, because I always won. Now you start to believe in yourself, believe in your quality. If not, it's difficult to balance belief and quality."
Ukraine international Mudryk, who was close to joining Arsenal before he made the move to Chelsea, has featured in five of the Blues' six league games this season, starting twice.
The 22-year-old scored 10 goals in 18 appearances for Shakhtar during the first half of 2022-23 prior to sealing his big-money move to the Premier League.
Speaking before Chelsea's Carabao Cup third round tie against Brighton at Stamford Bridge, Pochettino said: "The problem is we can't buy confidence at the supermarket.
"It's about time. You know how our brains work - it's about little by little, creating situations where we can provide the trust and the confidence and the belief.
"That is one aspect you work on, the psychology of the player, and that can make the difference to provide the players with confidence to touch the ball and score. It's a small example."