Manchester United manager Jose Mourinho has confirmed that valuable midfielder Marouane Fellaini is a doubt for Tuesday night's game against Basel as Champions League football returns to United's schedule for the first time since an early group stage exit in 2015.
Fellaini has divided opinion among fans since his 2013 arrival from Everton, but Mourinho has been a fan since day one of his reign and went as far as stating that he 'feels weaker' without the Belgian.
"Fellaini didn't train yesterday [Sunday], and let's see if he can today," the United boss said as he addressed the media ahead of the game at Old Trafford.
"He's a very important player for me, much more important than what you can imagine.
"I feel weaker without Fellaini in my squad, it doesn't matter if he is on the bench or if he is on the pitch. If his condition improves he will be selected because I need him. But I cannot say at this moment [if he will be available]."
Fellaini, who scored for United against Leicester last month, picked up a calf issue while on international duty. He missed the weekend's 2-2 draw with Stoke as a result.
But while Fellaini will be included in the squad if fit, Phil Jones and Eric Bailly both definitely miss out as a result of UEFA suspension. The pair have been Mourinho's preferred centre-backs so far this season, with Chris Smalling and Victor Lindelof to start against Basel instead.
"I think it's easier for him to play in the Champions League, it's more comparable to the Portuguese style of play than the Premier League," Mourinho said of Lindelof, a player who seemed to struggle during pre-season after his summer move from Benfica.
"He needs a bit of time for the Premier League, but step by step he's going to be there."
Unlike last season when Sergio Romero played in goal for most of United's European games, Mourinho has also confirmed David de Gea will retain his number one jersey for Tuesday.