"Gareth has had a bit of a hamstring [problem], hopefully he should be OK," manager Harry Redknapp told reporters at the club's training ground on Friday.
Bale missed Wales' friendly with Costa Rica on Wednesday with British media reports suggesting he had suffered a grade one tear to his hamstring training for the game, played in honour of the late Wales manager Gary Speed.
However, Redknapp said the injury was not that serious.
"He hasn't even got a tear in his hamstring, it's just a bit tight, but he should be OK. It shouldn't be a problem," said the Spurs boss.
Bale was due to train with Spurs on Friday as they attempt to bounce back from last Sunday's shattering 5-2 loss at rivals Arsenal.
Champions United are in fine form with five wins and a draw from their last six league matches.
Redknapp said forward Rafael van der Vaart and right-back Kyle Walker, who pulled out of their respective squads for England against Netherlands at Wembley on Wednesday, should also be fit.
"Rafa is hopefully going to train today, he feels a lot better," he said.
Third-placed Tottenham host United, who are second, looking for their first win against Sir Alex Ferguson's side since 2001.
Although Spurs were heavily beaten at Arsenal, they remain seven points ahead of their North London rivals in the race for third place and an automatic qualifying spot for next season's Champions League.
Spurs have 53 points while United have 61 with leaders Manchester City a further two points ahead.
