Andreas Christensen made a huge mistake which cost Chelsea a vital goal in Tuesday night's 1-1 draw with Barcelona at Stamford Bridge.
Antonio Conte's side deservedly took the lead through Willian in the first leg but a momentary lapse in concentration at the back allowed Leo Messi to equalise.
A misplaced pass by Christensen, 21, gave Iniesta the simple job of setting up Messi to side-foot past Thibaut Courtois.
The young Danish defender has been magnificent in west London this season and was preferred to captain Gary Cahill on Tuesday night.
Cahill, 32, was left on the bench and Cesar Azpilicueta - who also didn't cover himself in glory for Barcelona's equaliser - was handed the captain's armband in his absence.
Messi's 75th minute equaliser means Barcelona are now the clear favourites to progress to the quarter-finals.
It was the little Argentine's first goal against Chelsea in nine attempts.
Conte brilliantly answers harsh question about Christensen
Asked in his post-match press conference if he regretted starting Christensen, Conte responded: "No, absolutely not."
"I think Christensen's performance was a very good performance, an incredible performance. We are talking about a player who is only 21 years old here.
"It's great that he is able to play this game with maturity and personality," Conte continued, as per Sky Sports. "I am very happy. He was one of the best players tonight.
"It is very difficult to pick one player or another player but I think Christensen played a top game. I am very pleased with his performance."
Skip to 4:15 to see Conte's strong comments on Christensen.
Chelsea fans loved Conte's response
Blues supporters on social media appreciated the Italian coach publicly defending their rising young star.
It's fair to say that former manager Jose Mourinho may have responded differently.
The Stamford Bridge faithful was singing Conte's name throughout the 1-1 draw.
He may have fallen out with the board since winning the Premier League in May - but the 48-year-old coach still has the full support from the Chelsea fans.
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