Delhi Capitals returned as a vastly improved side to reach their first Indian Premier League (IPL) final but will need an extraordinary effort to upset Mumbai Indians on Tuesday after three unsuccessful attempts to beat the champions this season.

Mumbai, the tournament's most successful team, made the playoff with a match to spare and crushed Delhi in Thursday's qualifier to stay on course for a fifth IPL title.

Delhi had to overcome Sunrisers Hyderabad in Sunday's second qualifier to set up a summit clash with a side who beat them twice in the round-robin stage this season.

"Amazing, this is the best feeling ever," Delhi captain Shreyas Iyer said after Sunday's win.

"This has been a rollercoaster. A lot of ups and downs, we have stuck together like a family."

Against Hyderabad, Delhi showed they have the tactical flexibility to try new combinations, opening with Australian Marcus Stoinis and recalling Shimron Hetmyer in inspired moves that paid off richly.

"You can't have same set of routines. You have to keep chopping and changing," Iyer said.

"In the next game too, we have to play freely and maintain our temperament."

Mumbai under the captaincy of Rohit Sharma have looked familiarly formidable, their explosive batting line-up complemented by a fiery bowling attack led by India's Jasprit Bumrah.

"Having such a versatile squad, it gives me the option of changing the batting order," Rohit said after securing a place in the Dubai final.

"At times, if I want to rotate the bowlers, I can do that as well. The guys do understand their roles.

"It's not easy if you're not batting in certain positions, but we made it clear right at the start of the tournament that this is how the team is going to play and the guys are happy with that."