After their exertions in recent weeks, Mark Anscombe has decided to rest back rowers Nick Williams and Chris Henry, in addition to frontline backs Ruan Pienaar, Paddy Wallace and Jared Payne.
Forward trio Stephen Ferris, Lewis Stevenson and Declan Fitzpatrick are all sidelined through injury.
Callum Black and John Afoa will start in the province's front row at Parc y Scarlets, linking up with South African-born hooker Rob Herring.
Neil McComb retains his place in the second row beside the fit-again Muller, with Iain Henderson and Robbie Diack coming in for Williams and Mike McComish. Roger Wilson will again start at number 8.
Ireland squad members Paddy Jackson, Luke Marshall, Darren Cave and Craig Gilroy all come straight back into the back-line after impressing during the November internationals.
Jackson will partner Paul Marshall at half back, while Cave and Luke Marshall will combine in midfield. Peter Nelson will get another run at full-back, with Gilroy and Andrew Trimble lining out on the wings.
A strong bench has been named, including current Ireland internationals Best, Tom Court, Dan Tuohy and Tommy Bowe.
Development prop Ricky Lutton could win his second cap if he appears off the bench on Sunday afternnon, while McComish, Michael Heaney and Niall O'Connor will provide further cover.
In Simon Easterby's Scarlets side, Ulster face one of the biggest threats yet to their superb winning run which now stretches to 11 competitive games.
The Welsh region have won their last four league games. Their only defeat at Parc y Scarlets in their last 13 PRO12 fixtures was a 23-16 loss to Ospreys in September.
ULSTER (v Scarlets): Peter Nelson; Andrew Trimble, Darren Cave, Luke Marshall, Craig Gilroy; Paddy Jackson, Paul Marshall; Callum Black, Rob Herring, John Afoa, Johann Muller (capt), Neil McComb, Iain Henderson, Robbie Diack, Roger Wilson.
Replacements: Rory Best, Tom Court, Ricky Lutton, Dan Tuohy, Mike McComish, Michael Heaney, Niall O'Connor, Tommy Bowe.