On an Eden Gardens strip that had little to inspire the bowlers, Saxena exploited Bengal batsmen's poor temperament to bundle out the hosts for 263, with a first innings deficit of 168 runs.
Saxena took six for 53 but it was left-arm spinner Ankit Sharma who triggered the Bengal collapse with 3 for 53.
Following on, Bengal were 43 for no loss at stumps on the penultimate day as they still require 125 more to avoid an innings defeat and make Madhya Pradesh bat again.
But their batsmen's inability to stay at the crease that has been their major worry for last couple of seasons once again haunted them as they lost their last eight wickets for 68 runs to brighten MP's hope for a second consecutive outright win against Bengal in the Ranji Trophy.
Sharma gave the first breakthrough in the very second over of the day with a classic leg cutter that rocked Anustup Majumdar's offstump.
Playing sluggishly, Das completed his ninth firstclass century just before the lunch but only to be dismissed by Sharma.