Frank Lampard has no doubts Kai Havertz will thrive for Chelsea, but insists the Germany youngster must first get up to full fitness.

Havertz arrived in a reported £72million (€80m) deal from Bayer Leverkusen, though he has so far failed to spark into life at Stamford Bridge.

After an indifferent display in his debut against Brighton and Hove Albion, Havertz struggled to impose himself on the game as Chelsea went down 2-0 to Liverpool on Sunday.

Yet Lampard has no concerns over the 21-year-old, who he suggested is not fully up to speed.

"Kai has played various positions in career, as number nine, number eight and a number 10," Lampard told a news conference.

"He played lots off the right for Leverkusen and I have my own vision going forward.

"The key now is getting him fit. Kai, with the situation we are in we aren't in a position where we can wait. We need to get him fit, and it'll become very clear why he's here."

Chelsea spent close to £200m bolstering their squad heading into this season, though injuries have left Lampard without some big names. 

Havertz and Timo Werner have featured in both of Chelsea's league matches, but Ben Chilwell, Hakim Ziyech and Thiago Silva have yet to play, while Christian Pulisic has also been out.

However, Lampard confirmed he will be able to welcome back two of those players for the EFL Cup tie with Barnsley on Wednesday, with Chilwell and Silva, who celebrated his 36th birthday on Tuesday, set to be included.

"Chilwell is in the squad for tomorrow, Pulisic and Ziyech are getting closer," Lampard added.

"[Silva] is in the squad for tomrorow, so not sure if a present or not for him – he's getting fit, in the squad and I'll make a decision on how many minutes he may get in the game, what's best for him."