Black Cats claim point
The Latics will be wondering how they did not claim three points in the North East, but Mick McCarthy will be delighted with the way his side battled back.
Wigan looked well on their way to victory after half time substitute Jason de Vos gave them the lead after 69 minutes.
Sunderland had earlier been reduced to ten-men when Julio Arca had been dismissed before half time for two bookable offences, but they battled back and Downing levelled with 10 minutes remaining.
Wigan shaded the first period, but neither keeper was really stretched - although Nathan Ellington went close for Athletic and Downing shot wide, after a good run, for the home side.
The second half saw Wigan step up a gear, with Ellington and Lee McCulloch both causing a number of problems.
The breakthrough came on 69 minutes when de Vos scooped home Andy Liddell's corner, after everyone missed the ball.
Wigan then pushed forward looking for a second and Ellington again came close, but string of brilliant saves from Mart Poom kept 'The Duke' at bay.
Liddell and Jimmy Bullard were also kept out by the Estonian, who was have an inspired night between the sticks.
Sunderland then made Wigan pay for failing to convert their plethora of chances as they caught the away side on the break as Kevin Kyle was brought down by Ian Breckin - and referee Ray Oliver then red carded de Vos for foul and abusive language.
On-loan star Downing took on the responsibility and sent John Filan the wrong way to level.
Sunderland then had chances to win the game, with Kyle and Tommy Smith going close - but a late winner for the home side would have been an injustice.
The point means Wigan move fourth, while Sunderland leapfrog West Ham into seventh.