Following on from the men in white's win over Bourgoin at Ravenhill last Friday, Williams has kept faith with the same 22 and also included Bartholomeusz and Paul Steinmetz.
The Welshman has decided not to include team captain Rory Best, who has made the Irish Six Nations squad. The hooker has returned to pitch work this week as part of his recovery following the sprained ankle he sustained against Leinster in the Magners League last month.
The Ulster team and replacements will be selected later in the week.
ULSTER Squad (v Gloucester): Forwards (12) - Justin Fitzpatrick, Bryan Young, Declan Fitzpatrick, Nigel Brady, Stuart Philpott, Justin Harrison, Ryan Caldwell, Carlo Del Fava, Matt McCullough, Neil Best, David Pollock, Grant Webb.
Backs (12) - Mark Bartholomeusz, Simon Danielli, Bryn Cunningham, Mark McCrea, Tommy Bowe, Andrew Trimble, Paul Steinmetz, Niall O'Connor, Paddy Wallace, David Humphreys, Paul Marshall, Isaac Boss.