Wycombe stumbled into the next round of the Carabao Cup as a stoppage-time own goal from Jack Simpson earned them a 1-0 win at Leyton Orient.
It was a cruel way for an evenly-matched tie to end, although one goal always looked likely to decide the match.
Demetri Mitchell had to clear a Dan Casey header off the line from a fifth-minute corner.
Cameron Stones should have marked his senior debut with a goal in the 34th minute when Wycombe broke and James Tilley fed him in space – but his effort went high over the crossbar.
The returning Magnus Westergaard almost punished Orient a minute into the second half when he pounced on a defensive mix-up, but he put his shot into the side-netting.
Tayo Adaramola sent his 86th-minute effort narrowly off target after a breakaway involving him and Azeem Abdulai that started deep in the hosts' half.
Yet Wycombe inflicted the cruellest blow for Orient four minutes into time added on – a fine run and cross by Tilley was delivered into the area and captain Simpson could not get his feet out of the way, turning the ball into his own net.
Report supplied by PA Media.
Post-match reaction
Wellens: 'The last 20 minutes we just ran on empty'
Mike Dodds: "It gives insight to how the future looks" (BBC Three Counties Radio)
