The midfielder stooped to head home Harry Pell's cross just four minutes after George Boyd had fired the visitors in front from a Craig Mackail-Smith pass.
Rovers took a sixth-minute lead through a shot on the turn through Jo Kuffour. But Byron Anthony headed a Boyd cross past his own goalkeeper in the 23 minute before Posh defender Mark Little was sent off in first-half injury time for a second bookable offence.
Mackail-Smith looked set to win the game for Peterborough when sent clear on 87 minutes, but the striker shot inches wide as goalkeeper Conrad Logan advanced.
Rovers hit the crossbar through a deflected Will Hoskins shot in the second half as a fiercely competitive battle ended with honours even.
Little's two bookings came within three minutes of each other, and his second challenge with Stuart Campbell was reckless in the circumstances.