The former Red Devils striker singled out the Frenchman for praise after watching Ole Gunnar Solskjaer's side progress in the Europa League
Robin van Persie hailed Anthony Martial as "world-class" after Manchester United's win over Copenhagen and described him as "a joy to watch" in full flow.
United booked a spot in the Europa League semi-finals with a hard-fought 1-0 victory against the Danish outfit in Cologne on Monday.
Ole Gunnar Solskjaer's men had 14 shots on target during the game and hit the post twice, with the breakthrough finally coming via a Bruno Fernandes penalty in the first half of extra time.