Swansea manager Paul Clement says Roque Mesa will get a chance to prove himself.
The diminutive midfielder, signed from Las Palmas this summer, has struggled to receive regular playing time so far this season.
Mesa was at fault for Swansea conceding a late winner against Watford last month, but Clement denies that is the reason for his absence.
"Some people have questioned why he is not playing, but it was not because of the mistake against Watford," said Clement.
"He has been getting up to speed with things and I have told him he is going to start against United.
"He has been training hard and he deserves a chance in the team."
Source: tribalfootball.com