Thomas Tuchel has revealed he is worried about Tammy Abraham's nagging ankle injury after the Chelsea forward suffered a fresh setback in training.
Abraham has battled an ankle problem since hobbling out of Chelsea's 2-0 win over Newcastle at Stamford Bridge on February 15, with Tuchel claiming the striker had been harbouring an ankle issue since playing against Burnley on January 31.
The 23-year-old has made five appearances since that initial problem, but failed to complete Chelsea training on Thursday and will now miss Saturday's Premier League trip to Leeds.
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"Tammy still has ankle pain from the tackle against Newcastle, from the same injury," said Tuchel on Friday.
"He's still not 100 per cent comfortable. Yesterday he went off, the day before he was fine, yesterday he had some training.
"Honestly I'm a bit concerned because it's still the pain from the tackle against Burnley, so we're talking about a long time now where he does not really feel 100 per cent free and comfortable; I can see it in training.
"Even if he finishes training, I see that it's not 100 per cent, that he has trust or feels totally free.
"So yeah, I'm a bit concerned but at the same time I have 100 per cent trust in our medical department, those guys are fantastic and they take care of him now.
"It was a bit of a setback yesterday that he had to leave the pitch during the warm-up, but he gets all the time he needs.
"First of all, it's most important he feels safe, free, and zero pain, and then we can think about his comeback."
Brazil defender Thiago Silva has suffered a minor recurrence of his prior thigh problem so will also miss Saturday's Elland Road clash.
"Thiago also had a little setback in training," added Tuchel. "At the end of the training session, the day before yesterday, he felt at the very end something around the same area where he was injured.
"So we had to take him off and he's back into a transition phase but not back in team training. So he will be out."
'Pulisic important part of my plans'
Christian Pulisic has struggled for game time since Frank Lampard's sacking as Chelsea manager at the end of January, starting just one game as Tuchel oversaw an impressive run of results.
Newspaper reports have suggested the USA international could be set to leave Stamford Bridge, but Tuchel dismissed the notion insisting Pulisic was an important part of his long-term plans.
"When you sign and play for Chelsea, it is part of the job description. You have to be impatient because all of my players are competitors and are hungry to play. At the same time when you are not selected by the coach, you have to be patient.
"If he starts tomorrow and does brilliant, if he starts against Atletico and does two goals, maybe he is the captain.
"We have many games and he is in my plans. He has the potential to be decisive for us from the bench. As a beginner, can he improve it? Yes. But his job is to be ready like everybody else."
Havertz needs to stay in the 'little pockets'
Tuchel praised Kai Havertz ahead of Saturday's game against Leeds after the summer arrival impressed in recent wins over Everton and Newcastle at Stamford Bridge.
The Chelsea boss feels the Germany international is growing accustomed to his position which requires him to stay ahead of the play in Tuchel's system.
"The position between a nine and 10 is pretty much his best position. He has the freedom to drop, to switch positions. I feel very confident with him in high positions, I don't want to have him behind the ball.
"He needs to be high up the pitch and he feels comfortable behind opponents, between the lines, and in little pockets."