The United boss has seen a versatile Belgium international pick up a calf complaint.
That issue is probably going to keep Fellaini on the sidelines until into February and could bring an end to the speculation which has surrounded his future in the wake of Jose Mourinho’s departure from Old Trafford.
Not that Solskjaer has offered any indication that he is seeking to part with a stricken performer who continues to offer an ‘X factor’ to the United squad when fit.
The Norwegian said of Fellaini ahead of a home date against Brighton on Saturday: “He’ll probably be at least three or four weeks, he’s got a calf problem and that’s sad.
“There’s X factor in different players and we all know Felli’s X factor and he’ll be working hard to get back in when all the big games are coming as well.”
Solskjaer added on the overall fitness levels of his squad: “There’s not many issues, I think just small niggles as there always is at this point of the season.
“Chris [Smalling], Marcos [Rojo] just started running lightly so not fit yet.
“Alexis has trained all week so hopefully he’ll be available and Felli is the long-term one that’s out. He’ll be out for a few weeks.”
Sanchez has taken in only two appearances under Solskjaer so far, with the Chilean forward continuing to nurture niggling thumps.
He is still searching for the spark which induced United to snap him up from Arsenal a year ago.
Questions have been asked of him on a regular basis since his arrival, but his current boss believes a proven performer will come good once clear of injury issues and full of confidence.
Solskjaer said on what can be expected from Sanchez: “You have to ask him, a player loves to play football, doesn’t matter who you are and he’s been hindered by injury.
“I know how frustrating that can be and how eager you are to get back.
“Maybe in the Reading game at half-time he should have told me to come off because the next 15 or 20 minutes were a setback.
“But he’s champing at the bit in training. His attitude has been fantastic in training and I’m looking forward to seeing him, I’ve got loads of good players to choose from.”
United, who have gathered six successive victories under Solskjaer so far, will welcome Brighton to Old Trafford this weekend sat six points adrift of the Premier League’s top four and looking to drive their direction nearer and nearer to the Champions League spots.