Mumbai registered its fourth win in the league stage at Wankhede stadium on Tuesday after beating Pondicherry by 27 runs.
The title favourites have beaten Mizoram, Haryana and Madhya Pradesh in their first three games.
Asked to bat, Mumbai rode on a blazing half century by skipper Suryakumar Yadav (57 off 37 balls) to post a descent 171/6 on the board.
Their inform openers Jay Bista (29 off 21 balls) and Aditya Tare (20 off 14 balls) conjured 48 runs for the first wicket.
Chasing 172, Pondicherry had a pathetic start and were reeling at 29-2.
But then Parag Dogra (45 off 35 balls) and opener Arun Karthik (27 balls) tried to resurrect the innings with 28-run stand, before Karthik was dimissed by Shivam Dube.
Anand Subramanian (39 off 31 balls) and Dogra gave a scare to Mumbai, but their bowlers held their nerves to eke out a win.
Pacer Tushar Deshpande (2-29) and Shams Mulani (2-25) shared the spoils.
There are no matches on Wednesday and the action resumes on Thursday.
In the first game at the Wankhede Stadium, Meghalaya stunned Assam by four wickets.
At BKC, Madhya Pradesh defeated Mizoram by 86 runs.
In the second game at the same venue, Haryana defeated Bengal by five wickets as they chased the 123-run target with 17 balls to spare.
Yuzvendra Chahal, who came back to the Haryana team after national duty, returned with figures of 1-21.