Stephane Sessegnon struck deep into extra-time as Sunderland booked their place in the FA Cup fifth round with a 2-1 replay win over second-tier rivals Middlesbrough on Wednesday.
With the scores level after 90 minutes and the match heading for a penalty shootout, the Benin international aimed a right-foot drive into the bottom corner past Middlesbrough keeper Jason Steele.
Sunderland, revitalised in the Premier League since Martin O'Neill took over as manager in December, dominated the early exchanges but had to wait until the 42nd minute to take the lead against the north-east neighbours.
Forward Fraizer Campell, who scored Sunderland's goal in the 1-1 draw in the first meeting between the sides, laid the ball off to midfielder Jack Colback.
He took aim and blasted the visitors ahead with a powerful shot that went in off the underside of the bar.
Middlesbrough, who were being encouraged forward by a noisy home crowd, were level 11 minutes after the break. Lukas Jutkiewicz reacted quickly to a bouncing ball in the penalty area and volleyed past Sunderland keeper Simon Mignolet.
Both sides defended resolutely to force the match into extra time, but as legs began to tire, Sessegnon drove forward into the Middlesbrough penalty area and steered the ball home with minutes remaining.
Sunderland will host Arsenal in the fifth round.