Chelsea manager Thomas Tuchel praised his academy players for stepping up on short notice and helping the club to a 2-0 win over Brentford in the League Cup on Wednesday.
Teenagers Harvey Vale, Jude Soonsup-Bell and Xavier Simons were included in the starting 11 for the quarterfinal after a string of COVID-19 cases left the Chelsea squad depleted.
"They did well," Tuchel told reporters. "They hadn't trained for a week because the academy was closed for COVID-19. We invited them into training two days ago, so two sessions with us. They listened carefully and did their jobs, they did good."
The trio of academy players were taken off in the second half, with the game still at 0-0.
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Tuchel brought on regulars Jorginho, Reece James, Christian Pulisic, Mason Mount and N'Golo Kante in the second half to great effect, with James' cross leading to a Pontus Jansson own goal and Jorginho scoring a penalty in the 85th minute.
"We knew we could have five big changes with a lot of quality, and also fresh legs because they were not overused," Tuchel said.
"That helped us a lot and was needed. I'm a big supporter of five changes."
Chelsea was drawn against London rival Tottenham Hotspur in the semifinals.
"I think the Tottenham draw is nice for our fans, a London derby, very difficult but we are looking forward to it," said Tuchel.