The game started well for Montrose when Gary Fraser slotted them into the lead with 20 minutes played, but Austin pulled the Bayview men level when he went past Matty Allan, Greg Pascazio and goalkeeper Ross Salmon to equalise five minutes from the break.
Austin put his side in front from close range three minutes after the interval before Pascazio received a red card for a high challenge on Kyle Wilkie. Scott Mercer then thumped in a third and Austin made sure that he was getting the match ball when he flicked home 12 minutes from time.
East Fife manager Gary Naysmith said: “This is a terrific win on a day where we were slow to get going. The result is not one I am going to get fooled by as we can play a lot better.”
Montrose boss Paul Hegarty said: “We were the better team for the vast majority of the first half. The goal just before half-time changed things.”
Queen’s Parkmoved up to second thanks to a 2-1 win at Stirling Albion.John Carter volleyed the Spiders into the lead on 23 minutes, but Steven Doris levelled within a minute. On-loan Celtic kid Tony Ralston scored the winner from a tight angle on 57 minutes.
Annan slipped from first to third place in injury time when Elgin’s Craig Gunn headed home a Jordan Halsman cross to earn a 1-1 draw. The Galabank men had led from five minutes before half-time when Steven Black had risen highest to nod in a Matty Flynn corner.
Berwick Rangers hit back in the second half to earn a 1-1 draw at Clyde, Sean Higgins scoring for the home team with a well-struck drive and Blair Henderson levelling from close range.
Arbroath easily brushed aside East Stirling 4-0 at Ochilview. Andy Ryan swept home a Bobby Linn cross after seven minutes, with Linn netting the second from the penalty spot early in the second half after home defender Connor Greene was dismissed. Ryan added a third before substitute Martin Grehan clipped a fine pass from Sergio Alvarez past Richie Barnard.
Shire’s misery continued as they ended with only nine men as substitute Billy Vidler was injured.