Alli was rested for Spurs' midweek draw at Brighton as one of six changes made by boss Mauricio Pochettino, who must decide whether to pick regular FA Cup goalkeeper Michel Vorm or stick with Hugo Lloris.
Danny Rose (calf) is still missing while Harry Winks (ankle) is a long-term injury victim.
"I need to decide tomorrow the starting XI and the players in contention," said Pochettino on Thursday. "I have still not decided. We still need to assess players after the game.
"After training today everyone was good, only Harry Winks and Danny Rose still out. Now we need to decide who will play on Saturday afternoon against United."
Tottenham squad: Lloris, Vorm, Gazzaniga, Trippier, Aurier, Alderweireld, Vertonghen, Foyth, Sanchez, Davies, Dier, Wanyama, Dembele, Eriksen, Sissoko, Alli, Son, Moura, Lamela, Llorente, Kane.