Carragher believes United may have to replace Martial if they are to win the Premier League.
United are unbeaten in 17 games in all competitions and are closing in on Leicester in the race for a Champions League spot.
“Liverpool possess an attacking trio that is difficult to improve," He wrote in the Telegraph. "Can we say the same of United?
“I think they need another world-class player at the top end of the pitch.
“Martial's goal record has improved but I am yet to be convinced he is the man to fire them to a title challenge."