Skipper Rohit Sharma weighed in with a 45-ball 51, but Kolkata's spinners kept Mumbai's big hitters in line, restricting them to 141/5. Kolkata's recently prolific opening pair of Robin Uthappa (80 off 52 balls, 9x4, 3x6) and Gautam Gambhir, who came up with their fourth 50-run opening partnership on the trot, ensured a win with 8 balls to spare.
Mumbai's bid to qualify will suffer a further jolt as bowling spearhead Lasith Malinga is set to miss the rest of the IPL on national duty. Kolkata's third win on the bounce helped them pull away from the pack chasing the third-fourth spots, having themselves started with four straight loses.
Kolkata won the toss and elected to bat and straightaway benefitted from Mumbai's lack of a strong opening partnership. Only one part of the CM Gautam-Lendl Simmons has come good so far, with the West Indian making 38 and a match-winning 68 in the last two games. On the day, though, both openers were back in the hut within the powerplay overs.
The pitch encouraged a bit of turn and Gambhir got Shakib Al Hassan on as early as in the fourth over and from then on, a combination of Al Hassan, Sunil Narine, Piyush Chawla and Yusuf Pathan would bowl 13 of the next 17 overs.
The loss of early wickets and the lack of runs at the top meant Ambati Rayudu (33 off 27 balls) and Sharma had to play cautiously. Coming in at 35/2, the pair added another 35 but the runs came at a snail's pace, in 6.4 overs. Consequently, after 12 overs, Mumbai were 70/3, scoring at 5.83 an over. Sharma had made 11 off 22 balls at this stage.
Though Sharma and Mumbai's big buy Corey Anderson swung a few blows, taking 17 off a Chawla over and 16 off a Morne Morkel over, Kolkata were able to keep things quiet otherwise. Despite Sharma staying till the final over of the innings, Mumbai were never able to get away at the death, scoring just 48 of the last six overs, finishing with 141/5, despite having five wickets in hand at the end. Kieron Pollard could manage just 10 runs off the 11 balls, not hitting a single boundary.
Kolkata's chase benefitted from the purple patch of Gambhir, who had 54, 69 and 63* in his last three games, and fellow-opener Uthappa. The right-hander has also been in good form scoring 47, 65, 47 and 46 in his last four games, and was the brisker of the openers. As Gambhir laid anchor, Uthappa struck the ball cleanly, and the pair kept the boundaries coming in the powerplay overs.
Though Gambhir fell for 14 off 18 balls, he had put on 50 for the opening wicket and the target was significantly reduced. Uthappa continued to find the boundary, allowing the likes of Manish Pandey (14 off 21 balls) and Yusuf Pathan (16* off 12 balls) to play around him.
Kolkata's slow play almost got them into a bit of trouble at the end, where they still needed 42 off 30 balls on a two-paced track, but Mumbai had by then bowled out both Harbhajan Singh and Pragyan Ojha and had nobody to support Malinga from the other end.
With Simmons bowling the 16th over, Uthappa hit him for two sixes with the kind of half-checked drives that fly over the ropes when the batsman is in good touch, immediately bringing the equation to manageable levels. Though he was out bowled in the same over, Kolkata had enough wickets in hand to canter to a win.