The province's three other players who were involved in France with the Irish squad - Andrew Trimble, who has an injured finger, Neil Best and Simon Best, who is recovering from a heart scare - remain on the sidelines.
Monday's video analysis session of the 31-11 defeat at the Dragons was not a pleasant one for McCall and his players, who are currently bottom of the league table.
The Ulster boss has called for a big improvement from his side this week. Speaking after the Dragons game, he said: "Defensively we were not good at times. There were too many missed one-on-one tackles. And on the reverse of that, when we had ball in hand and were attacking, we made too many mistakes."
The re-introduction of the five Ireland players means Irish underage stars David Pollock, Darren Cave and Kieran Hallett drop out of Ulster's matchday squad. Former Northampton Saints centre Seamus Mallon has also returned to the squad after being omitted for the Dragons game.
McCall, who is hoping to guide Ulster to their first ever league win away to Llanelli, will name his starting line-up by noon on Thursday.
ULSTER Squad: Forwards - Bryan Young, Justin Fitzpatrick, Nigel Brady, Rory Best, Matt Miles, Tom Court, Justin Harrison, Tim Barker, Carlo Del Fava, Matt McCullough, Neil McMillan, Roger Wilson, Stephen Ferris.
Backs - Paul Marshall, Isaac Boss, Niall O'Connor, Paddy Wallace, Tommy Bowe, Seamus Mallon, Simon Danielli, Mark McCrea, Mark Bartholomeusz, Bryn Cunningham.