Elsewhere in the pack Damian Welch plays at flanker and a new lock combination pairs Wales under-20 captain Jevon Groves with the experienced Matthew Veater.
Behind the scrum Gareth Chapman, scorer of the winning try against Coventry, switches from centre to wing and Craig Morgan plays at full-back.
Saturday's game at the Wern Field reunites two clubs that first played each other over 130 years ago. In 1876-77 Merthyr were Cardiff's second ever opponents at the Arms Park. The records show that on 11 January 1877 Cardiff, then wearing their original black-and-white jerseys with the skull and crossbones motif, defeated Merthyr by one try and four touchdowns to nil. It was the club's third and final match of their inaugural season.
More recently, the clubs met in the fourth round of the Swalec Cup in 1994. Among Cardiff's try scorers in their 63-8 win at the Arms Park was Steve Ford. A later generation of the family, Luke Ford, will be one of Cardiff's replacements this weekend.
The game at the Wern Field, Ynysfach, kicks off at 2.30pm.
Team: Craig Morgan; Ryan Howells, Shaun James, Richard Jones, Gareth Chapman; Gareth Davies, Luke Evans; Richard Cornock, Rhys James, John Yapp, Matthew Veater, Jevon Groves, Damian Welch, Adam Powell, Nick Hampson
Replacements (from): Kieran Crawford, Phil Osborne, Kristian Gay, Patrick Palmer, Jake Thomas, Lee Jarvis, Luke Ford, Garyn Lucas