The win ensures RR will have two bites to the cherry in the Round of 16 to qualify for the IPL 2022 Final as they finish in second place with 18 points, just above Lucknow Super Giants thanks to a better rate net stroke.
The Royals will now face IPL 2022 best Gujarat Titans in the playoff Qualifier-I.
Defending champions CSK remain second in the table in ninth place with 8 points after suffering their 10th defeat of the season.
CSK got off to a stunning start as Moeen Ali (93 on 57 balls) brought in the second fastest fifty-something of the season to help them go 75/1 on the power play.
However, they lost steam once the restrictions on the pitch were lifted as the other batters failed to back the Englishman and RR played well to limit CSK to a 150/6 aggregate.
Fly-half Yashasvi Jaiswal (59 from 44 balls) then provided RR with a solid base before Ashwin (40 balls unrecovered from 23 balls) clinched victory with second place in the Player of the Match performance seal on the point table.
Rajasthan’s chase got off to an impressive start as Jaiswal smashed back-to-back fours over Mukesh Choudhary’s opening two deliveries in the opening round.
However, Simarjeet Singh (1/18) struck in the second over as this season’s leading scorer, Jos Buttler, (2) continued.
Jaiswal and Sanju Samson shared a stable 51-run partnership to help RR recover from this blow. But the strategic time-out worked in CSK’s favor as Mitchell Santner (1/15) took an excellent catch back after Samson (15 from 20 balls) smashed a delivery thrown straight at him in the 9th.
Devdutt Padikkal (3 from 9 balls) struggled to start and was castled by Moeen Ali (1/21) as he looked to play the slogsweep as RR was reduced to 76/3 in the 12th.
Jaiswal, 20, showed good maturity in the middle as he stuck to the ground shots only, hitting 8 fours in his innings to raise his half on 39 balls in the 14th.
The youngster then decided to up the ante as he hit Prashant Solanki for a six in the next but it was the bowler who had the last laugh as he then got Jaiswal caught (59 from 44 balls) square-legged deep to pick up his first IPL wicket.
Solanki (2/20) then doubled his total by catching Shimron Hetmyer (6) in deep midwicket to reduce RR to 112/5. However, Riyan Parag (10 on 10 balls) came out and shared an undefeated 39-point partnership with Ashwin to ensure there were no setbacks.
Earlier at the Toss, MS Dhoni opted to bat as CSK made a substitution with Ambati Rayudu replacing Shivam Dube. Rajasthan also made a change when Hetmyer returned to the team to replace James Neesham.
Trent Boult gave RR a good start by only offering 2 runs in the first set while letting Ruturaj Gaikwad (2) fall behind on the final delivery. Moeen Ali then came out and failed to get out of the mark on the first 4 balls he faced as Prasidh Krishna only gave up one run on the 2nd.
The floodgates were partially opened as Devon Conway broke a six and a four against Boult in the 3rd. But it was Moeen who went hammer and pliers after the RR bowlers as he smashed 3 fours and a six against Prasidh at 4th over.
Moeen continued his onslaught, hammering 2 fours and a six against Ashwin in 5th over, but booked his best for Boult in the power play finale. Moeen hit Boult for 6, 4, 4, 4, 4, 4, taking 26 runs in the most to help CSK go 75/1 late in the power play.
Moeen even scored the second fastest fiftieth of the season, out of 19 deliveries, during this assault against Boult (1/44). However, Rajasthan slowly clawed their way back after the strategic timeout as Ashwin (1/28) trapped Conway (16 from 14 balls) LBW in the 8th.
Obed McCoy then struck in his first over as he caught N Jagadeesan (1) midway with a slower shot. Yuzvendra Chahal then opened his account with Rayudu (3) caught off guard as CSK were reduced to 95/4.
Dhoni and Moeen then stitched up a regular 51-on-52 ball partnership to help CSK recover. The pair were eventually split in the penultimate as Chahal (2/26) made Dhoni (26 of 28 balls) catch long-range with a slower delivery.
McCoy (2/20) then ensured there was no century for Moeen (93 from 57 balls) as he surprised the versatile CSK with another slower delivery in the final as CSK could only display 150/6 despite this dazzling start. .