Substitute Ki Sung-Yueng dumped Chelsea out of the Capital One Cup with a 118th-minute winner at the Stadium of Light.
The Stamford Bridge side looked to be in control after Lee Cattermole's own goal in the 46th minute. Goal-line technology helped establish the ball had crossed the line.
Some redemption for his disallowed strike for England against Germany in the 2010 World Cup finals looked to be with Frank Lampard, but this time, the strike was awarded to the Sunderland captain.
Chelsea wasted a number of chances to seal their passage into the last four and were made to pay in the 88th minute.
United States international Jozy Altidore was unable to get a clear shot on goal, but the ball dropped instead for Fabio Borini to rifle in the equaliser from a tight angle.
That goal sent the tie into extra time and Mark Schwarzer twice saved well in the additional period. Ki, who won the trophy with Swansea last season, was on hand with two minutes left to slot home the winner for former Chelsea favourite Gus Poyet's side.
Afterwards, Chelsea boss Jose Mourinho said (per The Guardian):
We had chances and chances and chances but not enough goals. Maybe the way to rectify it is not to concede as many goals. We lose goals and the opponents come alive. We scored against Sunderland and afterwards we had two or three more chances. If we had scored then, goodbye, but we kept the opponents alive.
We've never lost a match because we didn't play or because the opponent was stronger than us. We lost every match because we produce, we don't kill opponents, we give them life and every opponent that plays against us knows they can score a goal and change the true result.
We play sometimes very well and have fantastic chances and don't score. It's the same story that repeats.
On target: 5-5