Ruddy takes over the goalkeeping position from regular custodian Peter Burke, who has been ruled out after damaging knee ligaments in training.
This is the only change to the Mayo team that proved too good for Sligo in the semi-final.
Back in 1989, during the course of the Connacht championship, Mayo lost the services of their goalkeeper at the time, Eugene Laffin, who was struck down by injury.
His replacement Gabriel Irwin proved to be an unqualified success, getting an All-Star award as Mayo qualified for the All-Ireland final, only to lose to Cork.
Ironically, both new kids on the block, Ruddy and Irwin, are from Glenamoy, while unfortunate victims Laffin and Burke both hail from Kiltymaugh.
Irwin was the first player from Glenamoy to play with Mayo in the senior championship.
Now Ruddy follows in his illustrious footsteps 14 years later, with manager Maughan obviously hoping that lightning will strike twice.
As expected, Galway have announced an unchanged side following their whitewash of Leitrim in the semis, with Michael Donnellan continuing at centre-back.
U-21 player Eamonn Towey, from the St Croans club in Ballintubber, will make his first championship start for Roscommon when they take on Offaly in Saturday's All-Ireland qualifier at Mullingar.
Towey, who has been introduced as a substitute in several games, takes over the left half-back position from Paul Noone, in what is otherwise an unchanged team.
Noone and two other squad members, John Nolan and David O'Connor, have been axed by manager Tommy Carr.
According to County Secretary Tom Mullaney, "the management decided to release the players in question for disciplinary reasons."
He confirmed that they would not be part of the squad travelling to Mullingar on Saturday, but he would not elaborate on exactly what the players had done to merit exclusion.
Tipperary will be without Liam England for their All-Ireland qualifier with Donegal at Croke Park on Saturday. The big, tremendously strong left half-back is in the US at present.
Full-back Sean Collum is receiving treatment for a knock that he took in the last game against Carlow, but is expected to line out.
Fermanagh, shocked by Down in the Ulster semi-final, have one injury doubt centre-back Justin Gilheaney for their All-Ireland qualifier with resurgent Meath at Clones on Sunday.
Gilheaney is troubled by a hamstring injury, and in the event of his failing to make it, the pivotal berth is expected to be filled by Cian O'Reilly.
Meanwhile, the Sligo County Board has set up a four-man committee to find a replacement for manager Peter Forde, who stepped down after his side's elimination.
MAYO (SF v Galway): F. Ruddy; A. Higgins, D. Heaney, G. Ruane; G. Mullins, J. Nallon, F. Costelloe; F. Kelly, J. Gill; T. Mortimer, D. Sweeney, A. Dillon; C. Mortimer, B. Malony, S. Carolan.
GALWAY (SF v Mayo): B. Donoghue; K. Fitzgerald, G. Fahy, R. Fahy; D. Meehan, M. Donnellan, S. og dePaor; K. Walsh, J. Bergin; P. Clancy, M. Clancy, J. Fallon; M. Meehan, P. Joyce, D. Savage.
ROSCOMMON (SF v Offaly): S. Curran; P. Cox, D. Casey, J. White; M. Beirne, F. Grehan, E. Towey; S. O'Neill, S. Lohan; G. Cox, G. Lohan, D. Connellan; S. Dunning, C. Mannion, F. Dolan.
TIPPERARY: v Donegal: Team: P. Ryan,. R. Costigan, S. Collum, L. Cronin, A.N. Other, D. Fanning, N. Fitzgerald, F. O'Callaghan, E.Hanrahan, A. Fitzgerald, K. Mulryan, P. Cahill, D. O'Brien, D. Browne, B. Hickey
MAYO (MF v Galway): R. Byrne; T. Howley, K. Higgins (Capt), J. Malone; S. Ryder, D. Sloyne, D. Padden; J. Gerard, S. O'Donnell; A. Kilcoyne, H. Gaughan, K. Costello; M. Ronaldson, M. Conroy, C. Boyle.