Mahendra Singh Dhoni's swashbuckling 84 went in vain as RCB edged CSK in a last-ball thriller to keep their play-off hopes alive in the IPL 2019.
Dhoni almost pulled off a sensational chase as he smashed five fours and seven sixes in his 48-ball blitz.
With defending champions Chennai needing 26 off the last over, Dhoni hit a four and three sixes but missed the final ball from paceman Umesh Yadav and ran to get runs through byes.
Parthiv Patel got his aim right to run out Shardul Thakur as Virat Kohli's side managed to win their third game.
"A whole lot of emotions. We thought we were outstanding with the ball till the 19th over mark. To be very honest, that was the last thing I would have expected," said a relieved Kohli.
"But anything can happen in the game of cricket. MS (Dhoni) did what he does well and gave us a scare."
The 37-year-old Dhoni lifted his side from a precarious 28-4 to bring them within touching distance of victory.
He built crucial partnerships including a 55-run fifth-wicket stand with Ambati Rayudu, who made 29, to try and calculate the chase.
"We did really well to restrict RCB below par. I think it was more of a calculation mistake that we lost wickets early on," said the skipper.
"T20 is all about taking risks, but you can still calculate. A lot of boundaries were needed, right now you can calculate, one run there, and two runs there and we just lost by one run. But you can also say we missed some boundaries."