A Tom Hopper tap-in and Brennan Johnson's opportunist effort put Lincoln City on top after the first leg of a hectic League One play-off semi-final against Sunderland.
An increasingly impressive Sunderland hit the woodwork twice in the space of a minute on the resumption.
But after Hopper's strike, Johnson charged down keeper Lee Burge's rushed clearance to make it 2-0.
Burge went to clear Tom Flanagan's under-hit backpass but smashed the ball straight at Johnson and the on-loan Nottingham Forest striker was able to collect and score his 13th goal of the season into an empty net.