Openers Ajinkya Rahane (38 in 32 balls) and Rahul Tripathi, who top-scored with a 31-ball 45, gave the Pune innings a solid launchpad by putting on 76 runs in less than 10 overs, but once the partnership was broken Mumbai had things under control.
Captain Steve Smith made 17, Mahendra Singh Dhoni, who had cracked a 34-ball 61 not out in a last-ball win two days ago, struggled in making 7 while another big-hitter, Ben Stokes, too fell for 17.
For Mumbai, leg spinner Karn Sharma was easily the pick with the wickets of both the openers at a crucial time, while Harbhajan Singh arrested the early run-flow to finish with fine figures of 1 for 20. Jasprit Bumrah bowled well again at the death to finish with 2 for 29.
Meanwhile, Harbhajan got to his 200th T20 wicket when he dismissed Smith in the 13th over.
More From This Section
Rahane, not in the best of form going into the game, and Tripathi got the visitors off to an impressive start.
Tripathi easily smacked Karn, playing his first game of the season in place of the injured Krunal Pandya, for a six over long on and the duo's exuberance resulted in Supergiant racing away to 48 in the first six overs.
The eighth over of the innings from Mitchell McClenaghan was very fruitful for the visiting side as 14 came off it, including three boundaries off the left-arm pacer, who had helped MI defend a small total of 142 against Delhi Daredevils just two nights ago.
Sharma packed off Tripathi as the batsman, who smacked two sixes and three fours, stepped out and lofted to deep extra cover for Kieron Pollard to complete a simple catch.
The bowler should have had the wicket of Smith, too, in the same over but for a dropped catch at deep square leg by Harbhajan. The Supergiant captain was on 8.
Smith, who had made 84 not out to lead Pune past the Mumbai total of 184 for eight in the first leg on April 5, struck a four off the next ball.
Three wickets in quick succession, between the 10th and 13th overs, pegged back Pune. Johnson cleaned up Stokes in his final over as the left-handed batsman's heave failed to connect and then Dhoni dragged an attempted pull shot off Jasprit Bumrah on to his stumps.
Pune added 40 in the last five overs and 18 in the final two.