Mumbai Indians 129 for 6 (Kerr 31*, Bhatia 30, Ahuja 2-5) beat Royal Challengers Bangalore 125 for 9 (Ghosh 29, Perry 29, Kerr 3-22, Sciver-Brunt 2-24, Wong 2-26) by four wickets

Exactly five balls later, Wong had the ball, Kerr was at long-on, Ghosh mistimed another heave, and Kerr pouched the catch several yards inside the boundary rope. Wong's smile to Kerr, brimming with appreciation, said it all.

Kerr has stepped up for Mumbai Indians at the end of the league stage, when pitches have started to tire out and assist spinners, and when Mumbai's best spinner in the early stages - Saika Ishaque - hasn't been able to continue her form from the first five games.

On Tuesday, Ishaque started with deliveries that were flat, around the 85-88kph mark, and she didn't get any success against the frontline batters.

Enter Kerr in the seventh over, when Smriti Mandhana had started to open up after collecting boundaries off the quick bowlers. Kerr went around the wicket and slowed one down at 77.6kph, which Mandhana went back for and miscued to the wicketkeeper with a leading edge.

Tossing the ball up is one of Kerr's strengths anyway, and the lack of pace on this pitch was going to trouble the batters when trying to manufacture power for the big hits. In her next over, Kerr flighted one even more, at 74.3kph, and with Royal Challengers desperate for runs after crawling to 59 for 2 in the 11th over, Heather Knight tried to clear the long-on boundary but was caught comfortably a few yards inside the rope for 12.

"I felt like I got going all right at the start of my innings reasonably positively and wanted to kick on because the overs were running out and we needed a few boundaries," Knight said later at the press conference. "I just probably picked the wrong ball as I was going for a slog sweep and it was a little bit further, and I tried to go for the sight screen.

"She [Kerr] bowled really well and she's a world-class bowler and varies her pace really well, and spins the ball both ways as well. It wasn't the easiest of wickets, it was a little bit slow, definitely hard to get going as a batter. That's the sort of wicket where you want to punch out 140 to make it competitive and give your bowlers something to bowl at."

On Tuesday, she unleashed her deceptive wrong'un again when Kanika Ahuja stepped out in the 15th over. Kerr bowled it so slow and wide of the left-hand batter that Ahuja didn't even bother to try and make her ground after missing with her big swing. Kerr's celebration after the stumping was a steely-eyed stare to Ahuja, as if to say, "this googly gets the best in the business, you better not try to go after it".

"When I first got here I was thinking, 'ten an over is a good day'. So the pitches are slowing up a little bit and getting some more turn," Kerr said at the post-match presentation. "But some world-class batters are batting in this competition on pretty good wickets with short boundaries and they can hit the ball a long way. It's about trying to deny that and going along the tournament I have worked out different plans that give me the best option to be successful."

Kerr returned for her last over at the death, and nearly got her fourth wicket too, before she took Ghosh's catch herself. And then she flung herself to her left while sprinting from long-on four balls later to save two runs, adding an Ellyse Perry-like halo to her all-round image.

And all this came well after her first big effort in the field on the day, when she ran out her Wellington team-mate Sophie Devine, who had hammered 99 off 36 three days ago - even if the throw went to what looked like the wrong end initially, with Devine and Mandhana nearly coming face to face.

About three hours later, Kerr had led Mumbai from a slightly worrying 73 for 4 to the finish line by top-scoring with an unbeaten 31 off 27. She scooped Mandhana to the fine-leg boundary when Mumbai needed six to win from 24 balls and would have hit the winning runs, too, had Mandhana not bowled five wides later in the same over.