The Kirkcaldy side, inspired by a hat-trick from top scorer Paul McManus, recorded a 4-2 victory over the 10-man Wasps at the end of a dramatic 90 minutes.
Rovers took the lead after only three minutes, McManus latching on to a superb through ball from Brian Fairbairn before sending a precise lob over the head of Alloa keeper Gary McGlynn.
The home side's second goal, after 18 minutes, arrived in controversial circumstances with the stand-side linesman flagging for a foul on Fairbairn. Referee Crawford Allan, however, allowed Fairbairn to advance and send in a cross which was driven home by Neil Jablonski as the Alloa defenders waited in vain for the whistle to blow.
John Ovenstone however pulled one back fro Alloa on the half hour with a powerful header from a John Stevenson corner, and Stevenson himself restored parity with a well- struck 25-yarder three minutes later.
McManus took advantage of a mix-up in the Alloa defence to make it 3-2 early in the second half, and he put the result beyond doubt with a goal from the penalty spot in the 69th minute after Ovenstone had lashed out at the grounded Scott Crabbe. Ovenstone received a straight red card for his indiscretion.