Frank Leboeuf has slammed Kai Havertz for his poor start to life at Chelsea, insisting the £70 million ($61m) midfielder is "almost invisible" on the pitch.
Chelsea beat off competition from a whole host of top European clubs to bring Havertz to Stamford Bridge from Bayer Leverkusen in the summer transfer window.
The Blues tied the 21-year-old, who became one of the top players in the Bundesliga during his time at BayArena, down to a five-year contract after forking out a lofty fee for his services, and Frank Lampard has wasted no time in testing his skills in west London.
The Germany international has already featured in 17 games across all competitions for Chelsea, but has only managed to contribute four goals and four assists to their cause, leading to question marks over his impact.
Havertz's latest underwhelming display came during a 2-1 defeat to Wolves at Molineux on Tuesday night, as the young playmaker struggled to affect the game in any meaningful way before being hauled off for Mateo Kovacic in the 71st minute.
Leboeuf does not believe that a big-money signing has shown any indication of living up to his price tag as of yet, and has suggested that he should have adjusted to his new surroundings by now.
Asked to assess Havertz's performance at Wolves, the former Chelsea defender told ESPN: "Almost invisible. I touched on the point some weeks ago. We heard Frank Lampard say, 'no, we need to give him time'.
"But I don’t know, it’s something that I don’t like, the way sometimes it feels like he’s not there, that he’s not trying to compensate for a lack of confidence with a desire or just being a warrior, showing us that, 'okay, I’m not good at the moment, but I’m going to fight for the club and not be invisible.'
"We share texts during the game and we were wondering if he was on the field. You can be bad – [Timo] Werner didn’t have a good game – but we saw him trying to get something going.
"We don’t see Havertz getting anything. I’m very concerned about that guy.
"I don’t forget the price they paid and I know he’s only 21 but we see players who arrived last summer who didn’t need much time to adapt and being very influential.
"I don’t understand what Havertz is doing right now but I want answers."
Havertz will be back in contention for a place in Lampard's line-up when Chelsea play host to West Ham in a London derby on Monday.