Chasing a victory target of 171, KKR were sailing along at 121 for no loss with Gautam Gambhir (54) and Robin Uthappa (65) cruising along before losing an incredible six wickets for addition of two runs in a space of nine deliveries (eight legal ones).
Scorecard KKR vs RR:
Shane Watson (3/21) and Pravin Tambe (3/26), including a hat-trick, scripted a remarkable collapse which the jam-packed Motera will remember for a long time to come.
The Shah Rukh Khan co-owned outfit never recovered from that telling blow as they were restricted to 160 for six in the stipulated 20 overs, losing their fifth game in the tournament. With a defeat like this, it will be very difficult for KKR to make a comeback. Rajasthan with 10 points from seven games stay firmly in contention for a semi-final berth.
It was a complete harakiri by the KKR batsmen as they snatched defeat from the jaws of victory with some mindless batting.
Watson scripted the turnaround at the start of the 15th over. Gambhir tried to loft him over extra cover but only got a thickish edge which was pouched by Sanju Samson.
With the third ball of the over, Uthappa who was in belligerent mood flicked one straight down Rajat Bhatia's throat. After a gap of another delivery Watson bowled a perfect leg-cutter to send Andre Russell (0)'s middle-stump cartwheeling.
Suddenly from 121 for no loss, KKR slumped to 122 for three but the drama was far from over.
The 43-year-old Tambe then pulled the rabbit out of the hat as he first bowled a wide googly which fooled Manish Pandey (0), who was stumped wide down leg-side.
Yusuf Pathan (0), who has forgotten when he last played a good knock, gave a simple return catch to Tambe. The wily old fox completed his hat-trick when his flipper found Ryan ten Doeschate (0) plumb in-front as KKR were now down in the dumps at 123 for six. It was as good as over for them at that point.
Watson kept his cool as he bowled a brilliant final over when 17 runs were required giving away only six runs.
However till the 14th over, it looked like a walk in the park for the Knights before they were hit by the 'Bolt from the Blue'.
Opener Uthappa was in punishing mood while skipper Gambhir complemented him with a well-crafted half-century as the duo laid the foundation of what looked an imminent comprehensive victory with a 121-run opening stand.
Uthappa's innings was laced with five boundaries and three towering sixes while Gambhir also played his part with six boundaries and a six to his credit.
It was the Karnataka dasher who started the onslaught with a flurry of boundaries as Royals' opening bowlers Shane Watson and Tim Southee faltered in length.
Uthappa was fed on his legs and he repeatedly clipped them in the arc between mid-wicket and mid-on.
Gambhir was content to play the second fiddle at the other end as Uthappa went berserk from the outset.
Uthappa reached his 50 hoisting rookie leg-break bowler Rahul Tewatia. Once he reached his 50, he played a slap shot to hit Rajat Bhatia into the sightscreen.
Gambhir gaine in his confidence as he took on the spinners Pravin Tambe and Tewatia hitting them for boundaries before dispatching Rajat Bhatia into the stands.
Little did they know as to what was to hit them when Watson took the ball in the 15th over.
Earlier, a collective effort by Rajasthan Royals batsmen saw them reach a respectable score of 170 for six after being put into bat by Gambhir.
In-form openers Karun Nair (44) and Ajinkya Rahane (30) provided a solid start while Sanju Samson (37) and skipper Watson (31) also made useful contributions to prop up the score.
Sunil Narine was again the pick of the bowlers grabbing two for 28 in four overs while R Vinay Kumar also got a couple wickets despite being smashed for 42 in four overs.
Rahane flicked Vinay off the very first ball of the match to start the innings in right earnest. In Yadav's second and fourth over of the innings, he carted the pacer for a four and a six off successive deliveries.
When Narine dropped one short, he drove the 'Mystery Man' through the covers as Royals reached the 50-run mark.
Having reached 30 off 22 balls with the help of three fours and a six, Rahane looked set for a big knock before it was cut short by a direct throw by Narine from short fine leg position. Rahane who was running to the striker's end could not make it despite a full stretched dive. The opening stand between Nair and Rahane yielded 52 runs in 6.3 overs.
Young Nair however carried on in his calm and calculative manner as he added another 53 with the talented Samson. He may not be one of the explosive players on the block but find of Karnataka's triumphant Ranji season certainly has the technique to play top quality bowling. On two occasions, he used his feet to sweep Shakib al Hasan's deliveries.
He also got a six with a mis-hit off a Yadav full-toss that flew over deep square leg boundary.
However the wily Shakib got his revenge when he cleverly bowled it wide outside off and the batsman had no chance with keeper Robin Uthappa completing the stumping. Nair's 44 came off 35 balls with four boundaries and a six.
Sanju played a few streaky shots as he got a couple of boundaries early on in the innings of Andre Russell.
Having scored 37 off 29 balls, Samson fell while facing the 30th delivery as he was holed out at deep mid-wicket boundary trying an ugly hoick off Narine.
Skipper Watson played his hand as he hit a couple crushing sixes off Vinay --- one over long off and other straight into the sight screen.
But Russell's antics of stopping on his delivery stride before completing the delivery broke his concentration as he was holed out in the deep with Suryakumar Yadav taking a well judged catch at the boundary line. Watson's 31 came off 20 balls with two fours and equal number of sixes.
However it Rajat Bhatia's six off the last delivery that took Royals' score to 170.