Gritty half-centuries from Faf du Plessis and Shane Watson propelled Chennai Super Kings to their record eighth Indian Premier League final.
With 148 to win, Chennai banked on an 81-run opening stand between Du Plessis and Watson to get over the line with an over to spare in the second qualifier.
The Mahendra Singh Dhoni-led side set up a title clash with Mumbai Indians, who beat Chennai in the first qualifier earlier this week.
"The way Faf got going, I could take my time getting into rhythm...I could take a couple more balls to find my feet," Watson, 37, said after his team's 100th IPL win
"There's huge positives about age and experience, and that's the way CSK has played, from the top with MS (Dhoni) and Stephen Fleming (coach).
"We know what to do in different situations, we've made the most of our experience," Watson said of his team that has been labelled as 'Dad's Army' for having quite a few 35 plus players including their 37-year-old skipper.
The South African captain smashed his 12th IPL fifty which included seven fours and one six but soon fell to Trent Boult.
Watson got to his half-century with a six off Keemo Paul before leg-spinner Amit Mishra ended the 32-ball knock.
"I reckon I almost ran three there (the early run-out chance). I have to laugh at myself because it was terrible running," said Du Plessis, who was named man of the match.
Chennai bowlers led by Dwayne Bravo set up a solid platform for victory after restricting Delhi to 147 for nine. Bravo returned impressive figures of 2-19 from his four overs.
He was well supported by fellow quick Deepak Chahar, spinners Harbhajan Singh and Ravindra Jadeja who all claimed two wickets each.