However, Virat Kohli and Tillakaratne Dilshan smashed brilliant half-centuries as the thriller snaked its way towards a tantalising finish. Shaun Tait almost sealed it for the Redbacks when he captured three wickets in the penultimate over, but Arun Karthik smashed a winning six off the last ball to seal the final last four spot on Wednesday.
Harris had laid the foundation when in walked Callum Ferguson (70 off 43 balls) and the pair put together a 114-run second wicket partnership that guided SA Redbacks to 214-2, the highest total recorded in Champions League Twenty20.
RCB appeared to have almost clinched it when Tait imposed his express pace to wrest control only for Daniel Christian to let it slip away with the final delivery of the stunning contest.
Gayle and Dilshan began well before Kohli took up the challenge in stunning fashion.
When Kohli's astonishing 36-ball 70 ended, RCB still needed 50 for victory in five overs. With 18 needed off the last two overs, Tait snapped up three wickets in the 19th over. He yorked Dilshan for 74 and took two more before the final twist.