Batting first, Chennai rode on Dhoni's 35-ball unbeaten 58 to post a competitive 168 for four. Albie Morkel (3/32) then spearheaded a disciplined bowling effort to restrict Delhi to 135 for nine at the MA Chidambaram Stadium.
Mohit Sharma, Ravichandran Ashwin and Dwayne Bravo picked up two wickets each as CSK grabbed the top spot again.
In reply, Delhi were off to disastrous start as they lost the dangerous Virender Sehwag to Sharma off only the second ball of the innings.
It was a short, wide delivery and Sehwag went for the cut only to get a thin edge through to the wicketkeeper.
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There was a surprise at the top of Delhi batting order, with stand-in skipper David Warner (44) sending Johan Botha ahead of him.
Botha followed 15 runs later, top-edging a sweep off Ashwin. Next to go was Kedar Jadhav whose predetermined shot off Albie Morkel landed in Dhoni's gloves. The dismissal ended a horrible night for Jadhav, who dropped a catch and missed a run-out besides his failure with the bat.
Morkel then sent back Ben Rohrer in a soft dismissal to leave Delhi reeling at 63 for five in the 10th over.