After 14 wickets had fallen for 157 runs in the first match on the temporary drop-in pitch when South Africa defeated Sri Lanka by six wickets, India bowled Ireland out for 96 with four overs to spare.
Rohit helped allay fears the pitches imported from Adelaide were too helpful to the quicker bowlers, however, easing his way to 52 from 37 balls with three sixes and four fours ahead of one of the most anticipated games of the tournament against Pakistan on Sunday.
After Rohit won the toss on an overcast morning, Ireland were immediately in trouble as they slumped to 46 for six.
Only Gareth Delaney offered any real defiance in the face of an attack in which fast bowler Jasprit Bumrah was again virtually unplayable, capturing two for six from his three overs and beating all the batsmen in the air or off the pitch.
Delaney, batting at number seven, scored 26 from 14 balls including a four and six from consecutive balls from left-arm paceman Arshdeep Singh before he was run out. Only three other Ireland players reached double figures.
After Virat Kohli had been quickly dismissed for one, Rishabh Pant (36 not out) batted with typical impudence, scoring the winning runs with a reverse sweep for six.
Bumrah, named man-of-the-match, said the ball had initially seamed around with pace and bounce.
"Once the seam goes down the pitch does settle down," he said. "You have to be prepared to bowl in all conditions."