Iyer, who cracked 153 in the first innings of the 40-time champions' previous game against Bengal, was given a reprieve by MP when on 10 and he took full advantage of the largesse to remain unconquered after hitting 15 fours and two sixes. The match was called off when the hosts were 311 for four.
At the other end was teenager Sarfaraz Khan, with an unbeaten 52 after adding 106 runs for the fifth wicket with Iyer, who faced 181 balls and batted for 258 minutes.
Had 20-year-old Iyer been caught at gully by Ankit Sharma off Avesh Khan when Mumbai were on 42 for one, the visitors could have put some pressure on the home team, but the chance was grassed. The centurion Iyer and opener Aditya Tare (57) took the team's score past the 100-run mark with a second wicket stand of 89 runs.
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But Iyer and Siddesh Lad (43) dashed their hopes with a stand of 95 for the fourth wicket.
For MP, medium pacer Puneet Datey was the most successful bowler with figures of three for 43 in 13 overs.
MP had to be content with three points from the game that took their overall tally to eight from five games, while Mumbai secured one point from the draw to increase their tally to 11.
Mumbai: 404 and 311 for four in 76 overs (Shreyas Iyer 142 not out, Aditya Tare 57, Sarfaraz Khan 52 not out; Puneet Datey 3/43).
Madhya Pradesh: 538 for 7 declared
Points: MP 3; Mumbai 1.