And the 'Candy Stripes' now await either Cork City or Wexford Youths in the 2008 final, the winners guaranteed a place in next season's Setanta Sports Cup competition.
In what proved an entertaining semi-final at Terryland Park, a venue where Derry netted four goals without reply on their recent visit, team boss Stephen Kenny made no fewer than NINE changes from the side which lost to Rovers.
Out of the starting line-up went keeper Gerard Doherty, defenders, Kevin Deery, Clive Delaney, Peter Hutton and Stephen Gray; midfielder Ruaidhri Higgins and forwards Thomas Stewart, Niall McGinn and Mark Farren.
In came Darren Quigley, Aaron Callaghan, Mark McChrystal, Eddie McCallion and Sean Hargan in defence with Barry Molloy and Owen Morrison in midfield and Sammy Morrow and Kevin McHugh leading the front line.
While the visitors certainly deserved to win the tie, they lived dangerously on occasions and the tie remained wide open until the final 18 minutes when a Sammy Morrow penalty and a goal from substitute, Niall McGinn, in the 38rd minute decided the affair.
Interestingly, Derry actually squandered an earlier penalty when Mark Farren, who entered the fray as a substitute for Owen Morrison in the 64th minute, failed to beat Galway keeper Gary Rogers with his first kick of the ball.
Galway, who were clearly spurred on by the memory of that harrowing 4-0 home league defeat, did well during the early stages and new signing, Jesper Jorgensen, who arrived on loan from Danish side, Kolding FC last week, made an immediate impact on his home debut.
A burst of pace saw him cruise past Eddie McCallion in the sixth minute before he was brought crashing down to earth by Derry 'keeper, Darren Quigley, but referee Mark Gough dismissed home claims for a penalty.
Derry struggled to get into their stride but Ciaran Martyn did force Rogers into action before Galway forced a succession of corners which almost brought reward when Fitzgerald volleyed narrowly over the bar.
Quigley could only parry John Russell's shot minutes before the break but Jorgensen couldn't force in the rebound.
Sammy Morrow then had Derry's best chance of the half when Kenna and Fitzgerald jumped for the same ball and left Morrow with a clear run at goal, however, Rogers came to the rescue with a vital save.
Morrow did have the ball in the net ten minutes after the break but he was adjudged to have been in an offside position while, at the other end, John Lester forced a great save from Quigley as Galway again forced a number of corners.
In the 72nd minute, the Dublin referee awarded the visitors a spot-kick and on this occasion Morrow stepped up to drill the ball home to give Derry a vital breakthrough.
And the visitors ended the game as a contest when substitute, Niall McGinn, entered the fray to make an impact in the 83rd minute, the winger catching Galway out on the break with a superb injection of pace before guiding the ball past Rogers.
GALWAY UNITED - Rogers; McCulloch, Kenna (Molloy, 74 mins.),Fitzgerald, Conneely; Davoren, Lester, Russell (Glynn, 85), Foley, O'Shea; Jorgensen (McBrien, 85).
DERRY CITY - Quigley; Callaghan, McChrystal, McCallion, Hargan; McGlynn, Martyn (McGinn, 36 mins.), Molloy, Morrison (Farren, 64 mins.); Morrow (Higgins, 85 mins.), McHugh.
REFEREE – Mr. Mark Gough (Dublin).