Mumbai Indians have sealed the final play-offs spot in the Indian Premier League with a 59-run victory over Delhi Capitals at Wankhede Stadium.

Delhi, who needed a win to keep their playoffs hopes alive, folded for 121 in 18.2 overs on a tricky wicket in reply to Mumbai's competitive total of 5-180 on Wednesday.

Gujarat Titans, Royal Challengers Bengaluru and Punjab Kings have already qualified for the playoffs, while there'll be frustration for Delhi, who became the first team in IPL history to miss the playoffs after winning their first four games.

Delhi didn't get momentum from the onset in their run-chase as Faf du Plessis, who led the side in the absence of ill Axar Patel, and Lokesh Rahul fell inside the first three overs.

With the ball gripping on the surface and favouring the spinners, Mitchell Santner (3-11) had Nigam caught off his own bowling and Jasprit Bumrah (3-12) pinned Stubbs leg before wicket for three to seal the game.

Delhi had earlier kept Mumbai in check at 5-132 with two overs left before Suryakumar Yadav (73no) and Naman Dhir (24no) excelled in the final two overs, which produced 48 runs for the home team.

Dhir smashed fast bowler Mukesh Kumar (2-48) for two fours and two sixes after Yadav had started the 19th over with a six to complete his half-century off 36 balls.

Sri Lankan fast bowler Dushmanta Chameera (1-54) then gave away further 21 runs in the final over to give Mumbai a decent total to defend.

"We let it slip in the last two overs," du Plessis said. "Momentum is a real thing in cricket. The way they counter-punched to get almost 50 in the last two overs ... undoing the work of the first 17-18 overs, we lost that momentum."