Invited to bat, Punjab openers Murali Vijay (42) and Manan Vohra (38) put on 78 runs in 8.2 overs to lay a strong foundation for a big score but other batsmen failed to capitalise and the hosts setled for 161 for six.
Ravindra Jadeja (2/30) removed both the openers but it was West Indies' seamer Bravo (4/22) who turned it around for the Lions by dismissing big-hitting David Miller and Glenn Maxwell in space of three balls in the 12th over.
Bravo accounted for two more batsmen in the last over and became the only player in IPL to have a combo of 1000 runs and 100 wickets.
Lions lost Brendon McCullum (0) in the very first over of their chase when the Kiwi batsman was stumped by Saha off Sandeep Sharma but the visitors went about their business calmly and overhauled the target with 14 balls to spare.
Finch stroked the ball with authority and did not spare a single Punjab bowler. The pitch at IS Bindra stadium was conducive for strokeplay and wayward bolwing by Punjab players only helped the Lions.
The Australian punished Punjab bowlers with 12 shots to the fence before being stumped off left-arm spinner Pradeep Sahu. At that stage Lions needed only 45 runs for eight overs and Finch had done his job nicely.
Karthik lost another partner in Jadeja, who was run out after scoring 8 runs, but it allowed India's Under-19 captain Ishan Kishan to bat against a quality bowler like Mitchell Johnson.
The young left-hander scored only 11 runs but showed that he has the heart to fight. Karthik and Bravo (2) ensured that there were no more hiccups for the Lions.
Karthik hit seven boundaries in his crucial unbeaten knock.
