Chennai managed to post 132/4 in 20 overs; credit to 66-run fifth wicket between Dhoni (37 no off 29 balls) and Rayudu (42 no off 37 balls) when other batsmen found going tough.
The defending champions didn't get off to a good start, losing three wickets in the Powerplay, as MI skipper Rohit Sharma used five different bowlers in the first five overs. Faf du Plessis (6) got one from Rahul that bounced a bit more as his cut went straight to substitute fielder Anmolpreet Singh at backward point.
Suresh Raina's (5) attempt to slog Jayant Yadav resulted in a skier which the bowler took with ease.
Shane Watson, who struggled for form, played a trademark pull off Jasprit Bumrah, but fell going for a big hit off Krunal Pandya, taken brilliantly by Jayant Yadav running backwards from his mid-on position. Murali Vijay attempted to consolidate in Watson's company and succeeded to an extent, before being stumped by Quinton de Kock off Rahul Chahar for 26 (26 balls, 3X4).
The visiting team kept things under control in the Powerplay, restricting CSK to 32 runs while picking up three wickets.
At the halfway stage, CSK barely managed to reach 50, which was a sign of their struggles.
Dhoni hit the first six of the match in the 14th over, lofting Jayant (1/25 in 3 overs) over long-on. Rayudu, on the other hand, hit three fours and a six and concentrating taking the singles and doubles with boundaries hard to come by.
The CSK skipper smashed Lasith Malinga for two huge sixes in the penultimate over to provide impetus to the CSK innings, which was stymied by the MI bowlers, especially the spinners.
MI leg-spinner Rahul Chahar continued his impressive season, with a superb spell of 2 for 14 in his quota of 4 overs. He kept the batsmen on a leash with turn and bounce.