Put into bat after a 25-minute rain-delayed start, Chennai rode on Raina's brilliant attacking half-century and his 54-run quickfire partnership from just four overs for the third wicket with his captain Mahendra Singh Dhoni (13).
Chennai lost a bit of momentum in between with quick dismissals of Raina, Dhoni and Ravindra Jadeja (8) but they still scored 181 for eight with Faf du Plessis remaining not out on 33 from 18 deliveries.
Raina came in at the fall of other opener Brendon McCullum (4) in the second over and after settling down, he set the Chinnaswamy Stadium on fire with some lusty blows all over the park. He hit four boundaries and six sixes in his 32-ball knock.
Raina struck three sixes off successive deliveries in the 13th over bowled by leg-spinner Yuzvendra Chahal. He reached to his fifty with the first six of the over in the second ball and then followed up with two more.
Chennai then lost Dhoni and Jadeja in quick succession -- in the 15th and 16th overs. Dwayne Bravo (5) and Ravichandran Ashwin (5) also did not last long but du Plessis held one end together to take his side to a challenging total.
For Bangalore, Chahal was the most successful bowler by grabbing three wickets though he conceded 40 runs in his four overs. Iqbal Abdulla took two wickets while Mitchell Starc, Harshal Patel and David Wiese got a wicket each.