In the other match between Vidarbha and Hyderabad, host captain and stylish middle order bat VVS Laxman failed to shine and was out for 13 as his side was skittled out for 138 by Vidarbha.
A big crowd turned up at the Secunderabad Gymkhana to see former captain Ganguly in action. But Mumbai won the toss and batted first.
Ganguly, however, picked up two wickets for 13 runs and was pick of the Bengal bowlers even though Ranadeb Bose also grabbed a couple of wickets.
Mumbai lost four wickets by tea and were 141 for four in 57 overs. Defiant show by Sohail Kukreja (55), Bhavin Thakkar (68 not out) and Prashant Naik (73 not out) steadied the ship and the last two batsmen added unbeaten 163 runs for the fifth wicket.
In the other match, Vidarbha inserted Hyderabad after winning toss and dismissed the hosts for a paltry 138 in 53.5 overs in their first innings.
Vidarbha medium pacers exploited the early conditions and forced Hyderabad batsmen to commit mistakes.
Hyderabad captain and star batsman V V S Laxman (13) fell cheaply, while Ambati Rayudu also could not make his mark. But thanks to all rounders Kaushik Reddy and I S Reddy, Hyderabad was able to put up a 100-plus score on the board.
Kaushik, facing 70 balls, hit 33 with the help of four fours.
IS Reddy hit 32 off 114 balls with the help of three hits to the fence.
For Vidarbha, right arm medium pacers Alind Naidu (5-25) and Sandip Singh (3-28) hustled the Hyderabad batsmen with their sharp bowling and shared eight wickets.
However, Vidharbha also started their reply shakily, losing three wickets for just 16 runs at tea. However, thanks to a 41-run fourth wicket partnership between Amit Deshpande and Harshad, Vidarbha reached 76 for four in 24 overs.
Mumbai: 259/4 in 86 overs (Sohail Kukreja 55, Bhavin Kakkar 68 n.o., Prashant Naik 73 n.o., S Ganguly 2/13, Randev Bose 2/47).
Hyderabad: 138 in 53.5 overs (Kaushik Reddy 33, I S Reddy 32, Alind Naidu 5/25, Sandip Singh 3/38). Vidharbha 76/4 in 24 overs.