League One leaders Luton saw a run of six straight wins come to an end following a 1-1 draw with Coventry at Kenilworth Road.
Matty Pearson headed the Hatters ahead with just 16 minutes on the clock, before Coventry substitute Jordan Shipley equalised 11 minutes before half-time.
The Hatters are still five points clear of second-place Barnsley with 12 league games remaining, following the Tykes' goalless draw with Portsmouth on Saturday afternoon.
However, the result will come as another pleasant surprise for Sunderland, who were the real winners this weekend following their 2-0 win at Bristol Rovers.
The Black Cats are now two points off Barnsley and seven behind Luton, with a game in hand on both.
Jack Ross' side will also travel to Barnsley next month, meaning promotion to the Championship is still well within their grasp.
Below Sunderland, Pompey's draw with the Tykes means Kenny Jackett's side have now gone eight league games without a win.
Portsmouth are now three points behind the Black Cats, having played one game more.
Further back, Lee Bowyer's Charlton were the only other side in the top six to win over the weekend, following a 2-1 victory at bottom of the table AFC Wimbledon.
The Addicks have also played one game more than Sunderland, though, and are six points behind the Black Cats.