"It will be a huge honour to make the mark," said Watkins. "The boys are determined to put Saturday's defeat against Leicester behind them and what better way to bounce back than by beating our arch rivals, the Ospreys, in a local derby. They don't come much bigger than this."
Watkins is one of four changes to the side which lost to the Tigers replacing Dafydd James who is nursing a knee injury. In the forwards Dafydd Jones replaces Alix Popham, Adam Jones replaces Vernon Cooper and Craig Dunlea comes in for tighthead prop Deacon Manu.
Scarlets: Barry Davies; Mark Jones, Regan King, Gavin Evans, Matthew Watkins; Stephen Jones, Dwayne Peel; Iestyn Thomas, Matthew Rees, Craig Dunlea, Adam Jones, Scott MacLeod, Simon Easterby (capt), Gavin Thomas, Dafydd Jones
Replacements: Deacon Manu, Ken Owens, Inoke Afeaki, Alix Popham, Liam Davies, Ceiron Thomas, Darren Daniel
Ospreys: Lee Byrne; Nikki Walker, Sonny Parker, Andrew Bishop, Shane Williams; James Hook, Justin Marshall/ Jason Spice; Duncan Jones (capt), Barry Williams/Richard Hibbard, Cai Griffiths/Andrew Millward, Brent Cockbain/Mike Powell, Alun-Wyn Jones/Jon Thomas, Ryan Jones/Lee Beach, Richie Pugh, Filo Tiatia
Replacements: Richard Hibbard/Barry Williams, Cai Griffiths/Andrew Millward, Alun-Wyn Jones/Mike Powell, Lee Beach/ Tom Smith, Jason Spice/Martin Roberts, Shaun Connor, Stefan Terblanche
Referee: Hugh Watkins (WRU)