Manchester United manager Louis van Gaal has revealed that Anthony Martial's hamstring injury is "not heavy".

The 20-year-old Frenchman pulled up during the warm-up ahead of last night's Europa League last-32 second leg against FC Midtjylland at Old Trafford.

The striker was swiftly replaced with youngster Marcus Rashford, who went on to mark his debut by scoring two goals in a 5-1 triumph.

After the game, when asked about the extent of Martial's injury, Van Gaal told reporters: "I have to say the first impression is it is not heavy.

"He can be tired because he is only 20 and he has played all the matches, so it is not so remarkable, but what is remarkable is he stepped down himself.

"[The warm-up injuries are] ridiculous but you have to cope with that. It is difficult also for the team because after David de Gea now Martial, they have both played a very good season and they have to be replaced and we are replacing them."

United now have 15 players on the treatment table.