Thomas Tuchel is adamant Romelu Lukaku will make a significant impact for Chelsea upon his return from injury, but insists the Blues must be patient with the striker.

Club-record signing Lukaku has netted four goals in 12 appearances since returning from Inter for a second spell at Stamford Bridge.

But, the Belgium international has missed the past month with an ankle injury.

He returned as a late substitute in the weekend draw with former club Manchester United, and could start against Watford on Wednesday.

Tuchel has no doubt of the quality that Lukaku will contribute to the Blues' cause when fully back up to speed.

But the head coach insists that for now, patience with the 28-year-old is a virtue.

"We showed with him and we showed without him that we're capable of scoring and capable of winning," Tuchel said.

"I think it's a process of adapting in both ways; the team will adapt to him and he will adapt to the team.

"The most important thing is that he becomes fit and gains fitness and a physical level that he can start for us. The rest, I'm pretty sure will take care of itself.

"I'm absolutely convinced and have zero doubts that he will have a huge impact on our team once he's back.

"He's pushing every single day and pushing everybody to try to be out on the pitch again. He tries to convince us that he's ready to start. 

"We gave him some minutes [against Man United], which helps him psychologically and this is very important, but he is determined and trains on a very high level. 

"Once we have the opinion that he's fully fit, I think he's ready to go and contribute what he can, which is a lot.

"We still believe that he can make the difference for us but at the same time, we will be patient."

Tuchel is also hopeful it is only a matter of time before Andreas Christensen signs a new deal with the club.

The defender, whose contract is set to expire at the end of the season, has made 13 appearances for the Blues in all competitions this term.

"We think we can have good news about Andreas," Tuchel added. 

"I understood the club wants the same, the player wants the same, the coach wants the same – to stay – and that’s why we need the commitment and can continue.

"We've been waiting a long time now for confirmation. 

"He tells us that he loves Chelsea, that he wants to stay and play a big part. He is a big part of a big club. I think he's a perfect fit and I hope that he's not done yet here. 

"He can still develop and be a big, big player. We want the commitment and hopefully, we get it."