Tiemoue Bakayoko falls asleep during matches and needs to improve if he wants to keep his place in the Chelsea team, according to club legend Frank Lampard.
Chelsea confirmed a second-place finish in Champions League Group C on Tuesday night after a 1-1 draw with Atletico Madrid at Stamford Bridge, while Roma beat Qarabag 1-0 at home to take top spot.
Atletico took the lead in the 56th minute when Bakayoko failed to track Saul Niguez at a corner that was flicked on to the back post by Fernando Torres, though Chelsea equalised on 75 minutes through Stefan Savic's own goal and created several gilt-edged chances to win.
After the match, Lampard said he still does not know what to make of Bakayoko, who became Chelsea's most expensive ever central midfield signing when he joined from Monaco for £40 million in the summer.
"He sleeps," Lampard said on BT Sport. "His concentration goes and at this level, you sleep for a second and it's an easy goal for Atletico.
"I don't know with Bakayoko. I think it's well documented that he hasn't settled quickly at Chelsea and English football in the Premier League as well and he has to come to grips with that.
"A moment's sleeping today doesn't work so he needs to improve but he's [Antonio Conte] got options. [Danny] Drinkwater will play as well but hopefully Bakayoko will improve."
Qualifying as runners-up means that, unless Sevilla or Spartak Moscow manage to overtake Liverpool in Group E on Wednesday, Chelsea's potential round-of-16 opponents will be limited to Barcelona, Besiktas or Paris Saint-Germain.
PSG smashed the record for goals in the Champions League group stage with 25 this season, with their star-studded front line featuring summer signings Neymar and Kylian Mbappe, but Lampard said that Chelsea will feel no fear.
"Obviously PSG, we're all talking about them and Barcelona, we all know what they have to offer," he added. "Chelsea fans will realistically look at Besiktas [as the easiest opponent] but it's a draw so who knows, and again who knows where all these different teams are.
"Even if Chelsea do draw one of the bigger teams then what a game and if you're going to win this competition you have to beat the big boys."
The round-of-16 draw for the Champions League will take place at UEFA's headquarters in Nyon, Switzerland, on Monday at 11 a.m. GMT.