Already out of contention for a play-off berth, RCB had nothing to lose but their top-order collapsed after being put into bat at the Chinnaswamy Stadium.
The big names like Chris Gayle, Virat Kohli and A B de Villiers were dismissed cheaply as RCB slumped to 34 for three in the fifth over. Opener Mandeep (52) and Head then stitched 71 runs for the fourth wicket to take the score past 150-run mark.
Mandeep hit four boundaries and a six in his 43-ball knock while Head struck three fours and five sixes in his 47-ball unbeaten knock.
The match began in a dramatic fashion with Gayle, who has failed miserably this season, getting out in the first ball bowled by Umesh Yadav. The West Indian tried to defend but the ball moved away and took a leading edge to land at the hands of KKR captain Gautam Gambhir at short cover.
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In comes Kohli and the India captain negotiated six deliveries for two runs before he was dropped by Piyush Chawla off the bowling of Yadav in the third over.
Mandeep, on the other hand, hit some lusty blows at the other end, including a six off Chris Woakes, but another wicket -- in the form of de Villiers -- fell in fifth over.
De Villiers, who also had a season to forget, hit a four off Sunil Narine but in the next ball, he was out clean-bowled while trying to play a sweep shot of a fullish delivery.
The duo batted through a rain-forced break of over 30 minutes with Mandeep reaching to his fifty shortly after resumption. But he got out immediately after reaching his fifty in the 16th over before Head took the score to 158 for 6 with some late big hitting.
For KKR, Yadav took 3/36 while Narine returned with figures of 2/29.