A superbly created and finished goal from Jake Keegan snatched all three points for Galway United at the City Calling Stadium.
In a very open first half, each side was guilty of poor finishing as opportunities were wasted at both ends.
While Galway defender Marc Ludden cleared off the line from a Gary Shaw header, and visiting 'keeper Conor Winn was worked by David O'Sullivan and Ayman Ben Mohamed drilled a half volley narrowly wide, the two clearest chances fell to Galway. Gary Shanahan on six minutes and Keegan on 34 should have done better.
Though Longford showed more endeavour from the start of the second half with Ludden making a terrific block to clear a drive from home skipper Mark Salmon seven minutes in, Galway stole what proved the winner with their first attack of the second half on 61 minutes.
Shanahan showed clever feet to nip past Powell down the right to whip over an excellent cross which Keegan finished to the net with a well-placed looping header.
Longford Town - Skinner; Sullivan, Gorman, Rossiter, Powell; Salmon, O'Connor, Rice (Shannon, 70), Ben Mohamed; Simon, Shaw (O'Sullivan, 11).
Galway United - Winn; Horgan, Oji, Walsh, Ludden; Shanahan, Byrne O'Leary, Molloy (Garcia, 55); Connolly; Keegan.
Ref - Sean Grant (Wexford)