The Lions' international recruits Sohail Tanvir (2-31) and Dirk Nannes (1-15 off 4 overs) were the pick of the bowlers.
A late cameo from Dinesh Karthik eventually guided Mumbai past the 150-run mark.
Brief Scores: Mumbai Indians 157-6 in 20 overs (M Johnson 30, R Sharma 27, D Smith 26; S Tanvir 2-31, D Nannes 1-15) vs Lions
Jayawardene praises 'mature' Unmukt
Young Indian batsman Unmukt Chand drew lavish praise from his Delhi Daredevils skipper Mahela Jayawardene, who said the teenager showed a lot of maturity in his 40-run knock that proved crucial in the team's win over Kolkata Knight Riders on Saturday.
"it was good knock. I saw him batting in the Under-19 World Cup final as well. That was also a fantastic knock. When we came here, I wanted to try and back him and give him an opportunity," Jayawardene said.
"But I wasn't sure where he is going to fit in that batting line-up. I think he is a very mature young cricketer who understands the game well. They were tough conditions but I think he handled them very well; so all credit to him. And hopefully he can improve further," added the Sri Lankan.