Rajasthan Royals recorded a comfortable seven-wicket victory over Chennai Super Kings, riding on Jos Buttler's unbeaten 48-ball 70 after their bowlers' parsimonious display in the Indian Premier League here on Monday.

The win kept RR's play-off hopes alive while leaving their beleaguered opponents on the verge of elimination.

RR restricted the three-time champions CSK to a modest 125 for five after being invited to bowl and then overcame the target in 17.3 overs, thanks to a 98-run fourth wicket partnership between Buttler and skipper Steve Smith (26).

It turned out to be an excellent day for Buttler, who sent back Faf du Plessis with an incredible catch earlier in the day.

Early wickets were the need of the hour for CSK while defending such a low total and the Mahendra Singh Dhoni-led side did exactly that by reducing RR to 28 for three inside five overs.

Ben Stokes (19) started on a bright note before inside-edging a Deepak Chahar delivery on to his stumps and an over later, Robin Uthappa was sent back by Josh Hazzlewood as the right-hander went for an extravagant scoop over wicketkeeper Dhoni, who was playing his 200th IPL game.

After shining early in the tournament, Sanju Samson continued to disappoint with the bat, departing for a duck.

Buttler and Smith joined hands and played cautiously initially. While Buttler was the aggressor, Smith played the second fiddle in the partnership.

Opting to bat, CSK never got going and lacked the fire power to put up a decent score after being reduced to 56 for four in 10 overs.

Ravindra Jadeja top-scored for CSK with a 30-ball unbeaten 35 and skipper Dhoni made a run-a-ball 28 while adding 51 runs for the fifth wicket.

Jofra Archer (1/20) was terrific with the new ball but he would be disappointed with his outing on the field.

Besides Archer, the spin duo of Shreyas Gopal (1/14) and Rahul Tewatia (1/18) were economical in the middle overs, while young Kartik Tyagi (1/35) too was impressive.

Dhoni's decision to bat first backfired as RR picked up wickets at regular intervals to make life difficult for CSK.

CSK lost the in-form Faf du Plessis (10) in the third over, caught by Jos Buttler off Archer and then an over later, Shane Watson was sent back by Kartik.

Opening the batting again, Sam Curran made 22 off 25 balls before being dismissed by Gopal.

After that, a lot depended on Ambati Rayudu but he too disappointed, perishing in the next over off Tewatia's bowling as CSK slumped to 56 for four.

Dhoni and Jadeja tried their best to resurrect the innings and then up the ante, but it proved to be too little too late.

Dhoni was run out in search of a double in the 18th over.

Kedar Jadhav continued to struggle with the bat as RR bowlers didn't give the CSK batsmen any leeway.

Brief scores:

Chennai Super Kings: 125/5 in 20 overs (Ravindra Jadeja 35 not out, Mahendra Singh Dhoni 28; Shreyas Gopal 1/14. Rahul Tewatia 1/18, Jofra Archer 1/20).

Rajasthan Royals: 126/3 in 17.3 overs (Jos Buttler 70 not out; Deepak Chahar 2/18, Josh Hazlehood 1/19).