The 20-year-old defender played his first Champions League game on Tuesday evening, starting for the Blues in our Round of 16 second leg against the current European champions at Stamford Bridge.

Unfortunately, an early error from Sarr enabled Khvicha Kvaratskhelia to score for PSG, effectively ending the Round of 16 tie. But that was a setback in what has otherwise been a very promising start to the Senegal international's career.

Having worked with Sarr at Strasbourg, Rosenior is in no doubt over the centre-back's quality and temperament.

‘I’ve worked with Mamadou for nearly two years and I'm so excited for his career – that's why he's here,’ said Rosenior in his pre-match press conference ahead of our Premier League to face Everton tomorrow.

‘But sometimes you have to go through negative experiences to improve. He will come back. He trained very well [on Thursday] and he's a massive part of our plans moving forward.’

Rosenior acknowledges errors in the defensive third, such as that Sarr made against PSG, are likely to receive greater exposure and analysis.

Yet our head coach appreciates a moment such as that, while painful, can be vital in a player's education, and Rosenior is confident Sarr will come out the other side better for it.

‘If you're a goalkeeper and you make a mistake, the chances are it ends in a goal, and it’s the same for defenders,’ explained Rosenior.

‘But players like Mamadou, Jorrel [Hato], who was magnificent [against Paris Saint-Germain] and has been top since I've been at the club, you want to give them opportunities to show what they can do and learn from mistakes.

‘We all make mistakes – me included – and you have to make sure you learn from them. In the long run, the pain that he's gone through will make him an even better player. That’s where Mamadou is at in his career.

'If he learns from his mistakes, honestly, it's so exciting what he can become as a player.’