Defending Indian Premier League champions Mumbai Indians continued their dismal start to the 2018 tournament with a seven-wicket to Delhi Daredevils.

The Indians began the competition with a pair of desperately tight reverses at the hands of Chennai Super Kings and Sunrisers Hyderabad, before another followed here as debutant Jason Roy inspired the visitors with an outstanding unbeaten 91 at Wankhede Stadium.

Suryakumar Yadav (53) moved up to open and made a half-century for Mumbai, while Evin Lewis (48) and Ishan Kishan (44) came close, but a middle order collapse left their total at 194-7 and the door ajar for the Daredevils.

Roy duly stepped up, working well with a trio of partners to lead the charge and reach Delhi's target with the final ball, earning their first win as the Indians' misery goes on.

MUMBAI MAKE HAY IN THE POWERPLAY

Having set targets that were just within reach of their opponents in the opening two matches, the Indians made sure to hit big from the off.

The Delhi bowling was as generous as the fielding in the powerplay and openers Suryakumar and Lewis made hay, with the latter - out for a duck on his debut just a week earlier - hitting four boundaries in a scintillating sixth over.

That partnership was finally ended in the ninth over as Lewis, having just taken Mumbai into three figures, slogged to Roy at long off.

INDIANS STUTTER TO SUB-200 TOTAL

Suryakumar made his 50 before being trapped lbw, with Kishan then picking up the baton and smashing seven boundaries - his stint ended by Dan Christian (2-35), who swiftly removed Kieron Pollard, next in, for a golden duck.

Indians captain Rohit Sharma (18) struggled to keep things moving, though, and the Daredevils belatedly had wickets falling with some regularity late on as the hosts' run rate dipped below double-digits in the penultimate over.

Given Mumbai's earlier dominance, a target of less than 200 kept Delhi's hopes of a fightback very much alive.

RELENTLESS ROY RALLIES TO TARGET

And it quickly became clear that the Indians' disappointing end to their innings would prove costly as Roy offered a strong response, smashing an early six out of the stadium.

Rishabh Pant (47) then arrived in the middle to build a partnership of 69 with Roy until the 20-year-old was caught by Pollard as he chased a half-century, bellowing his frustration as he departed.

A breathtaking Hardik Pandya dive halted Glenn Maxwell at 13 off six balls, but there was no let up from Roy and two boundaries, plus a nerve-wracking single, in the final over - with 11 required - got the job done.