"Merthyr came here and won in the cup last season so we know what we are up against," added manager Gavin Walker.
The Wanderers make one change in the front row with Chris Hole getting his first start of the season and with Gareth Knight reverting to the second row, Dan Crimmins returns at No 8. Jake Henry gets a game in the back row on permit from Cardiff.
There is one change in the backs. Ian Newbury starts and Dan Lovell drops to the bench. Amongst the subs Joe Russell and Joe Sullivan join the squad from the Development squad.
Glamorgan Wanderers: 15 Sean Cochlin 14 Joe Xiberras 13 Ciaran Driscoll 12 Charlie Johnson
11 Ian Newbury 10 Gareth Cull 9 Tim Cronin; 1 Chris Hole 2 Mike Catris 3 Mel Lewis 4 John George 5 Gareth Knight 6 Lee Highgate (capt) 7 Jake Henry 8 Dan Crimmins
Replacements: 16. Jac Hopkins 17. Joe Russell 18. Will Rees 19. Joe Sullivan 20. Dan Lovell