Thomas Tuchel has described Ousmane Dembele as a player at the "top level" amid reports Chelsea may make a move for the Barcelona star this January.
The France international, who is out of contract in the summer, is expected to leave the Camp Nou this month after failing to agree a new deal with the La Liga giants.
"With Ousmane and his agent we began [contract] conversations around July so it's been six months and a bit," Barcelona's director of football Mateu Alemany said this week.
"We've talked, we've talked, we've talked. Barca has made different offers. We've tried to find a way for the player to continue with us but these offers have been systematically rejected by his agents.
"In this scenario, he and his agents have been informed that he must leave immediately because we want players committed to this project and therefore we hope that a transfer will take place before January 31."
Reports in France claim Barcelona will demand around £16million for Dembele this month and Chelsea have been linked with a move for the 24-year-old.
Dembele worked with Tuchel at Borussia Dortmund and is understood to still admire the winger despite his injury issues; the Frenchman has played just a third of the minutes available over the past four-and-a-half seasons.
And the Chelsea head coach spoke glowingly about Dembele ahead of Chelsea's Premier League clash against Tottenham Hotspur on Sunday.
Tuchel said: "‘He’s a very good player, and I am very fortunate to have trained him in my time at Dortmund. It was only one year, it should have been longer, but I needed to leave and he decided to leave.
"We are not in close contact, we have met here and there because of his duties for the French national team when I was in Paris. We exchanged some messages.
"I have absolutely no idea why he is in this situation, I don’t know the detail, so it’s better not to talk."
