The forward hasn’t played since the 3-0 home defeat to Bournemouth in December, with illness initially given as the reason behind this.
However, his prolonged absence is unusual given how quickly other United players who have suffered with sickness recently, like Marcus Rashford, have recovered.
Ahead of the 2-2 draw with Tottenham last Sunday, Ten Hag simply said that Martial was not fit enough to play.
The Daily Mail are now reporting that the Frenchman is being forced to train away from the first-team as his manager does not believe he has regained sufficient fitness following his illness.
It is not uncommon for players lacking in match fitness to train alone, and it is not believed that Ten Hag is punishing Martial in perhaps the same way that Jadon Sancho was exiled.
However, the length of time it is taking for the 28-year-old to get back into shape is raising eyebrows, especially as United were hoping to sell him in January.
Martial’s contract is up in the summer and not expected to be renewed, meaning that his nine-year spell at Old Trafford is very likely to be over.
Though he has scored just 12 Premier League goals over the past three-and-a-half seasons, the forward still wants to stay and fight for his place, and Ten Hag is content to keep him for now due to the lack of centre-forward options at his disposal.
The club were hoping to offload him this transfer window and get his huge salary off their wage bill but there have very few offers for the player.
It remains to be seen whether Martial will be deemed fit enough to play in time for the Red Devils’ next game on 28th January, when they travel to League Two side Newport County for an FA Cup fourth-round clash.
For more stories like this, check our sport page.
Follow Metro Sport for the latest news on
Facebook, Twitter and Instagram.