Saurabh's 109, laced with 9 fours and 3 sixes, helped East rise from their 44-run deficit in the second innings to declare on 281 for seven in the final session of play.
West were 12 for one at close of play, requiring another 226 runs to win on the final day's play.
Starting the day on 321 for nine, the West innings' wrapped up on 322 in response to East's first innings score of 278.
But the 181-run fourth-wicket partnership between Saurabh and Sudip Chatterjee (99) was the highlight of the day as rest of the East batting failed to counter the West bowling led by Dhawal Kulkarni (4-28).
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Chatterjee was unlucky to miss out on his century after being run out by Shardul Thakur (2-70), who also brought Saurabh's downfall in the 76th over of the innings and soon skipper Manoj Tiwary called the players back.
With just the winning target in mind, the West Zone openers Aditya Tare (5 not out) and Vijay Zol (6) started cautiously.
But Dinda cleaned up Zol to bring to end the day's play as the game is poised for an interesting finish tomorrow.