Rabada, who had earlier dropped Iyer off his own bowling when the left-hander was on 23, finally had the batsman caught at deep square leg in the 13th over. Fast bowler Avesh Khan had Gill caught behind while Dinesh Karthik and Morgan both were clean bowled by Rabada and Nortje, respectively.
Ashwin brought the game closer when he had Shakib Al Hasan and Sunil Narine dismissed off successive deliveries before Tripathi’s straight six off the fifth delivery finally saw Kolkata through to the final.
Earlier, both Kolkata spinners Varun Chakravarthy (2-26) and Narine (0-27) bowled steadily in the middle overs and didn’t allow Delhi to accelerate. Shikhar Dhawan top-scored with 36 and Shreyas Iyer made an unbeaten 30 off 27 balls.
“Can’t change anything after the match,” a disappointed Delhi skipper Rishabh Pant said. “They bowled really well through the middle overs. We were stuck and unable to rotate the strike. Hopefully we can come back next year for a stronger season.”
Two-time champion Kolkata last won the title in 2014 when they beat Punjab Kings in the final. In a repeat of the 2012 final, Kolkata will meet Chennai Super Kings in Friday’s title game.