Mumbai's hopes of playing in the final of the inaugural Inter-state Twenty20 championship received a setback with Tamil Nadu's victory over Haryana on Wednesday.
The current position in Group B is that Tamil Nadu, Bengal and Mumbai are tied on four points, having played three matches each.
Tamil Nadu now play their last match against Madhya Pradesh on Thursday, while Mumbai play Bengal in their last league encounter.
If Mumbai beat Bengal and Tamil Nadu beat Madhya Pradesh, Tamil Nadu will be through as a result of their win over Mumbai earlier in the league.
If Tamil Nadu lose to Madhya Pradesh, though, then the winner of the Mumbai-Bengal match will play at the Cricket Club of India in Saturday's final.
And if Tamil Nadu beat Madhya Pradesh and Bengal beat Mumbai, then Bengal will be through on account of having beaten Tamil Nadu earlier in the league.