Martial, who has not played since December 9, is now ruled out until April having undergone surgery on a groin injury.
The 28-year-old will be out of contract at Old Trafford come the end of the season and may well have played his last game for the club.
It leaves Erik ten Hag with Rasmus Hojlund as his only fit striking option, and the Dane has just two Premier League goals to his name all season.
Martial, meanwhile, has netted a solitary goal in five Premier League matches for United this season.
Despite being so light on numbers up front, profit and sustainability rules (PSR) mean the club will not be able to bring in another face before the window closes.
Indeed, the Athletic has reported that not even a loan signing will be permitted during this transfer period.
“Club staff believe the risk of long-term punishment is not worth a short-term fix,” says the report.
Discussions took place about the best course of action for Martial’s injury and, while it was a problem that could have been managed on a game-by-game basis, the player’s preference was for surgery to rectify it.
This is Martial’s ninth season at Old Trafford and likely to be his last, having now played 317 times for the English record champions and scored 90 goals.
It is a poor return for a player who was signed as one of the leading 18-year-olds in European football back in 2015 for a fee of €60m including add-ons.
New signings in summer?
United, under new part-owner Sir Jim Radcliffe, will be hoping to have more spending power come the summer, with a new centre forward thought to be on the cards.
Ivan Toney is known to be of interest and the Athletic also cites Ajax’s Brian Brobbey as a target.
But, United fans who were hoping for a fresh goalscorer to arrive during this window and aid with a Champions League are going to be left disappointed.
That means fanciful links to Karim Benzema are likely to stay in the realms of fantasy.