MS Dhoni blasted a commanding half-century under pressure to help the Chennai to a comfortable 55-run win away to the Kolkata.
India captain Dhoni hit an unbeaten 66 and put on 109 in an unfinished stand for the fourth wicket with Subramaniam Badrinath (43 not out) as Chennai recovered from a poor start to reach 164 for three off their 20 overs.
In reply, Kolkata managed a feeble 109 all out to crash to their first defeat in three IPL matches.
Kolkata enjoyed a tidy start and secured an early breakthrough when Australian batsman Matthew Hayden (one) dragged a delivery from Ishant Sharma back onto his stumps.
Murali Vijay, who had promised much, was dismissed in similar fashion for 33 by Laxmi Shukla and Chennai slipped further when Suresh Raina was bowled for 18 by Brad Hodge.
At 55 for three and with his team in a spot of bother, Dhoni walked out to join Badrinath and steadied the innings with some sensible batting.
The run rate, a measly 4.4 at the end of the first five overs, gradually rose above the six-run mark and Chennai, with wickets in hand, were nicely poised for the push in the final overs.
Dhoni turned up the heat by first smashing Shukla for a six and two fours, treated Shane Bond with similar disdain and, with Badrinath chipping in with a six off the first ball, smacked Ishant for 16 in the final over, despite the duo suffering a frightful collision while completing a second run off the fourth ball.
Kolkata conceded 61 runs in their last four overs, Dhoni reaching his half-century – his fifth in the IPL – off only 28 deliveries.
Chennai carried their momentum into the Kolkata reply with Albie Morkel removing Hodge for a second-ball duck in the first over with the new ball.
Manpreet Gony, who replaced Sudeep Tyagi in the line-up, bowled Manoj Tiwary in the next over while Lakshmipathy Balaji and Justin Kemp ran through the middle order – Sourav Ganguly, Owais Shah, Angelo Mathews and Rohan Gavaskar all went cheaply – to leave the home side were soon tottering at 79 for seven.
The last-wicket pair of Ishant and Murali Kartik held up Chennai, but victory was eventually achieved when Kartik was run out.
Kolkata: Sourav Ganguly (C), Brad Hodge, Manoj Tiwary, Owais Shah, Laxmi Shukla, Rohan Gavaskar, Angelo Mathews, Wriddhiman Saha (W), Murali Kartik, Ishant Sharma, Shane Bond.
Chennai: Murali Vijay, Matthew Hayden, Suresh Raina, Justin Kemp, MS Dhoni (C) (W), Subramaniam Badrinath, Albie Morkel, Ravichandran Ashwin, Lakshmipathy Balaji, Muttiah Muralidaran, Manpreet Gony.