Last-minute replacement Adam Zampa helped Rajasthan Royals keep alive their slim chance of qualifying for the Indian Premier League playoffs after beating Punjab Kings by four wickets.

With a 7-7 win-loss record, Rajasthan finished the league stage fifth on Friday, outside the top-four playoff places. They need other results to go their way to qualify on net run-rate.

Punjab became the third team to fall out of contention, leaving six teams vying for three playoff berths.

Rajasthan reached 6-189 after Punjab made 5-187.

Punjab's $2.25 million signing, Sam Curran, ended the season with only 10 wickets in 14 games. Curran returned an expensive 1-46 but fared better with the bat in the death overs with an unbeaten 49 off 31 balls.

Punjab needed rescuing after falling to 4-50 in the seventh over. Fast bowler Navdeep Saini, playing only his second game, picked up 3-40.

Trent Boult claimed yet another powerplay wicket while Zampa, who stepped in for an injured Ravichandran Ashwin, was most economical.

The Australian international took 1-26 off his maximum four overs but more importantly claimed the big wicket of Punjab skipper Shikhar Dhawan, trapping him leg before.

Curran revived Punjab by adding 64 runs with Jitesh Sharma (44) and a brisk 73 with Shahrukh Khan. Rajasthan conceded 46 runs off the last two overs.

Young Rajasthan left-handers Devdutt Padikkal (51) and Yashasvi Jaiswal (50) shared a 72-run second-wicket stand after Jos Buttler fell for his third consecutive duck.

Buttler started the league brilliantly with three half-centuries in his first four games, but his form nosedived with five scores of zero in the next 10 innings and only one half-century.

Padikkal and Jaiswal were both caught at backward point.

Shimron Hetmyer then struck three sixes and four boundaries in a breezy knock of 46 off 28 balls. Hetmyer was caught low in the covers by Dhawan to give Curran a consolation wicket.

Dhruv Jurel smashed a straight six against Rahul Chahar in the last over to raise Rajasthan hopes of progressing in the tournament.