League Two Swindon dumped Wigan out of the FA Cup to reach the fourth round for the first time since 1996.
Swindon fell behind after Callum McManaman won a penalty for Wigan and was on hand to put the ball away when Ben Watson's spot-kick hit the post.
But Paolo Di Canio's side quickly drew level thanks to Alan Connell's header.
Swindon secured a remarkable win when Matt Ritchie's left-footed shot took a big deflection off substitute Paul Benson to beat Ali Al Habsi.
In an emotional interview with BBC Wiltshire on the touchline immediately after the final whistle, Di Canio dedicated the win to Swindon's fans and to his father, who died late last year, as supporters chanted the manager's name.
Swindon, who are in the League Two play-off places, were well worth their win against a Wigan side that showed nine changes to the team that lost to Sunderland in midweek.
Di Canio's men should have taken the lead as Raffaele De Vita seized on Adrian Lopez's misplaced pass and picked out Ronan Murray, only for the on-loan Ipswich striker to shoot straight at Al Habsi.
Paul Caddis's deflected cross then skidded past the Wigan goalkeeper's post, while Swindon full-back Callum Kennedy tried his luck from long distance.
Despite that promising start, Swindon went behind on 34 minutes after Aden Flint fouled McManaman in the area.
Watson's spot-kick rebounded off the post, but McManaman reacted quickest and slipped the ball beneath Swindon keeper Wes Foderingham.
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