John Egan struck 11 minutes from time to help Gillingham to a 1-0 victory over Leyton Orient to move through to the Southern Area final of the Johnstone's Paint Trophy.
Chances were few and far between during a quiet opening 15 minutes before Gillingham finally created the first opportunity on goal when Gillingham's Leon Legge headed over from a corner.
Three minutes later, Orient registered a reply though David Mooney, but the forward could only glance wide after being found by Gary Sawyer's cross.
Both sides were lacking an edge in the final third and that led to Orient's Gianvito Plasmati attempting to break the tension with an ambitious effort from 30 yards but he was always unlikely to test Stuart Nelson.
After seeing a free kick go narrowly over the crossbar, Shane Lowry was called into action up the other end to block a goalbound shot from Luke Norris before the first half ended with Plasmati forcing a stop out of Nelson with a close-range header.
Orient had the better of the action after the restart but Gillingham almost took the lead through Norris, who saw a volley breeze past the post.
As the match entered the final quarter, Sawyer, who had been a frequent threat for Orient, whipped another teasing cross into the penalty area where Bradley Pritchard poked the ball wide from close range.
The tie looked to be heading for penalties but with 11 minutes remaining, Gillingham took the lead when Egan rose above the Orient defence to head home his third goal in the space of seven days.
Dean Cox was thrown on for the visitors as they searched for a late equaliser but Gillingham held on to move one tie away from reaching the final at Wembley.
