After Ashok Dinda's 22nd five wicket haul in first class cricket enabled Bengal to restrict Mumbai to 229, Bengal scored 198 for 3 in 61 overs.
Tiwary scored an unbeaten 85 off 123 balls with 11 boundaries and a six. Sudip Chatterjee was patience personified once again with undefeated 67 off 177 balls with seven fours.
The duo added 142 runs for the 4th wicket after Bengal were in trouble at 56 for 3 having conceded 130 run lead. Effectively Bengal are 68 runs ahead with seven wickets in hand and two full days of play left.
Mumbai certainly have the upper hand as both Dhawal Kulkarni (2/43) and first innings wrecker in chief Shardul Thakur can use the morning conditions pretty effectively. Just like Dinda did today morning by getting four out of the five wickets.
He now has 34 wickets this season and four more required to complete a career haul of 350 wickets.
Dinda's figures read 21-6-88-5 while rookies Mukesh Kumar (3/56) and Amit Kuila (2/55) were the other wicket takers.
But highlight of the day was Tiwary' s 27th half century in first class cricket.
While Tiwary, who has always prove to be a thorn in Mumbai's flesh with his attacking batting. Strong off his pads, Tiwary was also in mood to play some good drives. Morning session on both days have proved to be productive and Bengal's best bets would like to put up a decent score in order to pose some challenge to the Ranji champions.
A defeat tomorrow would all but end their chances of qualifying for knock-outs.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)