Tom Beere struck in stoppage time to give AFC Wimbledon a narrow first-leg lead over Accrington Stanley in their League Two play-off semi-final.
The hosts' Lyle Taylor dragged a low shot just wide in a first half that did not produce a single shot on target.
Substitutes Tarique Fosu and Adebayo Akinfenwa struck the post for Accrington and Wimbledon respectively.
Beere's low finish gave the Dons the advantage going into Wednesday's return leg at the Crown Ground.
Accrington, who were denied automatic promotion on the final day of the regular season, arrived at Kingsmeadow on the back of five consecutive away wins.
But both sides struggled to get going in a nervy first half which lacked quality.
The Dons, who are appearing in the Football League play-offs for the first time since the phoenix club's formation in 2002, were playing on the 28th anniversary of Wimbledon's famous FA Cup win over Liverpool.
They grabbed a fifth win in six home games in the final moments of the game when Beere kept his cool to slot in past a crowd of players and net his first ever goal for the club.
The hosts had earlier appealed for a penalty, after the ball appeared to strike Accrington's Tom Davies on the arm in the area from a dangerous free-kick.