The France international missed the Red Devils' last two matches after picking up a hamstring injury in the warm-up prior to the Europa League victory over FC Midtjylland on Thursday.
But Louis van Gaal has revealed that the 20-year-old is in contention to return against the Hornets, while Matteo Darmian, who had been struggling with a shoulder injury, is another who could be brought back into the starting XI.
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"Martial can play and also Darmian can play. Maybe Chris Smalling can play. We have to wait and see for tomorrow.
"We have to build players up. You have seen how I did it with Marcos Rojo - 20 minutes and, the second time, 60 minutes, though he did not reach that. So it's not so easy. Playing in the second team is also a possibility.
"It was a kick [for Rojo]. A lot of players receive kicks and they can play the next match."