MUMBAI: Powered by Mahendra Singh Dhoni and Manoj Tiwary's quickfire partnership for the fifth wicket, Pune scored 41 off their last two overs to finish at 162/4.
Mumbai, who usually excel at chasing, made a mess of it.
While Pune progress to the final, Mumbai get another shot at it when they take on the winners of Kolkata Knight Riders and Sunrisers Hyderabad in qualifier 2 in Bengaluru on Friday.
The last match here was a run feast, Kings XI Punjab scored a tournament high of 230 and Mumbai fell only seven runs short. But on Tuesday, the Wankhede wicket played more true to its character, rewarding good bowling.
Ajinkya Rahane and Major Tiwary steadied the early wobble with an 80-run stand, but struggled to keep the run rate up. The first big hit came in the seventh over, when Tiwary hit Karn Sharma for a straight six. As the boundaries dried up, the duo resorted to running between the wickets to keep the scorecard ticking.
And while Dhoni did not get into the slam-bang mode instantly, he waited patiently for Mumbai to slip up. The hosts had come up with one of the most disciplined performances with the ball in the IPL, having conceded only 121 runs for three wickets in 18 overs.
Pune carried the momentum into the last over and took 15 off Jasprit Bumrah. Dhoni finished unbeaten on 40 off 26 balls.