Ex-Nottingham Forest player Riley Harbottle scored in the second half to give AFC Wimbledon the lead in the Sky Bet League Two play-off semi-final against Notts County at Meadow Lane.
Harbottle's goal secured a hard-fought 1-0 victory for Johnnie Jackson's team, setting them up nicely for the return leg at the Cherry Red Records Stadium next weekend.
Despite creating several opportunities, County manager Stuart Maynard will believe his team still has a chance to make it to Wembley.
However, Alassana Jatta's red card in stoppage time, for a foul on Alistair Smith, could be a major setback for Notts County.
With just one point separating the two teams in the final league table, it was always expected that the first leg would be a competitive affair.
Matthew Stevens came close to scoring for the visitors with a headed effort, while Conor Grant also threatened for Notts County but was unable to break the deadlock.
Both teams showed determination to take control of the match, but their final passes or touches lacked accuracy until Harbottle's crucial goal.
In the first half, Sam Austin almost set Jatta free on goal, but Joe Lewis made a crucial intervention. Jake Reeves missed a good chance for Wimbledon with a wayward header from a corner kick.
After Reeves' miss, County faced sustained pressure from Wimbledon but stood firm in defense. The game then saw end-to-end action, with both teams having chances to score.
Harbottle made the difference in the 59th minute by heading in Reeves' cross to give Wimbledon the lead.
Despite the setback, County kept pushing for an equalizer, with Jodi Jones coming close with a long-range effort that hit the post.
In the dying minutes, Grant had a chance to score for County but was denied by Wimbledon's defense before the final whistle blew.