The Belgian recently returned from more than three months on the sidelines with a hamstring injury by playing the full 90 minutes in the FA Cup replay win over Newport County.
However, he was left out of the matchday squad entirely for Saturday's North London derby win over Arsenal despite declaring himself fit for the match.
The Telegraph reports that he will also be left in England to work on his fitness while the rest of the squad travels to Turin for Tuesday's Champions League game.
The report goes on to speculate that his omission could have an impact on his ongoing contract talks with the club, with his current deal due to expire in 2019, although that does have the option of a further year extension.
Manchester City and Chelsea are rumoured to be monitoring the 28-year-old's situation, as he could be available for as little as £25m in summer 2019 if a new deal is not agreed before then.