Opting to bowl, a disciplined bowling performance helped Royal Challengers restrict Mumbai Indians to 141 for six in 20 overs.
Sri Lanka's spin legend Muttiah Muralitharan (2-24), medium pacers Vinay Kumar (2-34) and Harshal Patel (2-24) struck for Royal Challengers but the pick of the bowlers was fast bowler Zaheer Khan who gave away just 16 runs from his four overs.
While chasing, Royal Challengers made a cautious start with Gayle and Tillekaratne Dilshan (19) adding 48 runs for the first wicket.
Gayle placed his innings well. The maverick West Indian first carefully saw off fast bowler Lasith Malinga's first spell and launched himself into Pragyan Ojha (1-25), hitting the left-arm spinner for three consecutive sixes as 22 runs came off the 11th over.
Gayle and stand-in skipper Virat Kohli (36 not out) added 94-run stand for the unbroken second wicket stand that took Royal Challengers home safely.
In Image: Royal Challengers Bangalore's Muttiah Muralitharan, left and Chris Gayle celebrate the wicket of Mumbai Indians Dwayne Smith