Wanderers were twice been pegged back here at Adams Park for a 2-2 draw after Matt Bloomfield and Alex Revell's goals were cancelled out by Billy Paynter and Alan Sheehan.
Sheehan struck home from close range after a through-ball from Scott Cuthbert on 80 minutes to make it 2-2, capitalising on poor marking to level the scores.
Revell initially saw his penalty saved but nodded home from Gareth Ainsworth's cross to make it 2-1 after Kevin Betsy had won the spot-kick under a challenge from Jon-Paul McGovern.
Paynter levelled three minutes after the break after Matt Bloomfield had handed Wycombe a lead with an excellent strike on the stroke of half-time.
The midfielder latched on to an excellent through-ball from Lewis Montrose and finished in style for his first goal at Adams Park since November 2007 - also against Swindon.
But after Simon Ferry's blatant handball in the build-up went unnoticed, Jon-Paul McGovern crossed for Paynter to nod home.
Gary Waddock named an unchanged starting XI for the third game running, which means Tom Heaton and Alex Revell come head-to-head with their former club.
Wanderers: Heaton; Woodman, Mousinho, Hunt, Westwood; Betsy, Ainsworth, Bloomfield, Montrose (McLeod, 69); Pittman (Phillips, 55), Revell.
Subs: Arnold, Oliver, Keates, Harrold, Beavon.
Goal: Bloomfield (45+2)
Bookings: Woodman (54), Revell (78)
Swindon: Lucas, Cuthbert, Sheehan, Greer (c), Darby (Amankwaah, 74) McGovern, Ferry (Easton, 63), Douglas, Ward (Marshall, 36), Paynter, Austin.
Subs: Smith, Timlin, Jean-Francois, Nouble.
Goal: Paynter (48)
Bookings: Paynter (54), Marshall (90), Cuthbert (90)
Referee: Mr Stuart Attwell.
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