On-loan Middlesbrough winger Stewart Downing slammed home an 82nd minute penalty after Jason De Vos had brought down Tommy Smith, to hand Mick McCarthy's side a point.
De Vos, on as a replacement for the start of the second half for skipper Matt Jackson, was sent off to even up the numbers following the controversial dismissal of Julio Arca on the stroke of half time for a second bookable offence.
Cautioned in the eighth minute after reacting to a challenge by Andy Liddell, the former Argentina Under-20 international was adjudged to have dived when challenged by Jimmy Bullard and referee Ray Oliver produced another yellow card to the amazement of Arca's team-mates and the home crowd.
Wigan, content to soak up the pressure and rely on the counter-attack, almost snatched a ninth minute lead, Mart Poom denying Nathan Ellington with a brilliant diving save. Sunderland's response was immediate, Michael Proctor wasting a glorious chance by firing into the side netting with only John Filan to beat.
The Black Cats' goal bore a charmed life in the 35th minute, firstly Poom beat out an Ian Breckin header and then George McCartney cleared the follow up from Neil Roberts off the line.
Lee McCulloch headed just over after Arca had been dismissed and to cope with the numerical disadvantage, manager Mick McCarthy sacrificed striker Procter and Colin Healy to bring on defenders Stephen Wright and Paul Thirlwell.
Wigan forced the all-important breakthrough in the 70th minute when De Vos' looping header from Nicky Eaden's left-wing corner dropped just inside the post with Poom stranded.
The Black Cats keeper however saved well from Ellington and then produced another magnificent stop from substitute Gary Teale as Wigan threatened to turn the screw.
Sunderland though battled to the end and were rewarded with that late equaliser which moves them above West Ham in the chase for promotion.