Chelsea manager Thomas Tuchel confirmed that he played Timo Werner against Luton with the hope of building the striker's confidence - something Alan Shearer noticed on Wednesday night.
The Hatters twice led at Kenilworth Road with Reece Burke and Harry Cornick scoring either side of a Saul Niguez strike to send them in at half-time in control.
But second-half strikes from Timo Werner and Romelu Lukaku ensured that the Premier League side survived a scare to book their place in the quarter-finals.
After the game, Tuchel spoke about the displays of both Werner and Lukaku, singling out the German for particular praise and revealed why he played the duo.
"Timo played very well, I am happy for that, and Romelu got his goal. That is why we left them on the pitch," Tuchel said in his post-match press conference.
"These matches are, at the moment, the most important matches for them even if they think they should've played this match or this match.
"We want them to play with full focus and take this seriously because this is where you grow in confidence, where you can get your confidence. Timo did very well and Romelu got his goal so it's only positive."
Werner has struggled to nail down a regular starting role since Tuchel's arrival at Stamford Bridge and the arrival of Romelu Lukaku has only limited his opportunities further.
This season has seen find the net just seven times in 24 appearances in all competitions and has appeared only 11 times in the Premier League.
But Shearer, who was working as a pundit for the BBC during the match, confirmed that Tuchel's plan to boost Werner's confidence in this match clearly worked.
"It is a very good touch and a clever finish actually, but up until then, his performance was pretty poor," Shearer said.
"But you could tell, after that goal he was more confident, he was flowing around the pitch and his movement was a lot better and of course he sets Lukaku up for the winner too."
