Ulster are facing something of a mini-injury crisis ahead of the crunch Magners League clash against Leinster at Ravenhill on Saturday night (7.30pm).
With both Andrew Trimble and Tommy Bowe ruled out of the contest as they continue their rehabilitation from their respective hamstring problems, there are also doubts surrounding Isaac Boss (shoulder), Stephen Ferris (knee) and Paul Steinmetz (calf).
All three are currently rated as "50-50" by coach Mark McCall and should all three be ruled out, Ulster would be without some key players for a clash they must win to retain top spot in the league.
Boss was a major success for Ireland, starting in the victory over Australia and enjoying a sizzling cameo on the wing off the bench against the Pacific Islands while Ferris made his international debut in that match and Steinmetz makes the Ulster midfield tick.
Belfast Harlequins scrum-half Paul Marshall has been included in a 25-man squad which also sees his club team-mate Paul McKenzie retained following his impressive cameo in the victory against the Borders earlier in the month.
With Andrew Maxwell omitted from the squad as he struggles with his form, McKenzie could be in line to make his first start for his province.
Despite the disruptions, McCall hopes his side will benefit from the returning international players who all made significant contributions on the international stage.
"The players seemed pleased to be back, we are delighted to have them back and everyone in the squad seems happy to see each other again," said McCall. "Training has gone fine over the last couple of days and we have a group of players back who are full of confidence and self-belief, and that is a good thing in any sport.
"I have no doubt that in the coming weeks and months that they will have a positive knock-on effect on everybody."
McCall was full of praise for the eight players who won caps during the autumn series, an indication that Ulster is once again emerging as a serious powerbase in Irish rugby.
"Last autumn we were happy with our representation but Ireland didn't go so well and the players came back perhaps down in the dumps," added McCall.
"But this time, not only were we delighted with our representation but we were delighted with how they acquitted themselves.
"To a man they all delivered performances in a very good team performance and that is brilliant for them as individuals, it is brilliant for Ireland and hopefully brilliant for Ulster as well."
Leinster, meanwhile, have their own injury problems, with key play-maker Felipe Contepomi ruled out for six weeks with a knee injury. Christian Warner is expected to replace him at out-half.
Guy Easterby, however, returns to the squad after a jaw injury sustained last month while Girvan Dempsey has been given the green light having been forced to retire with head injury during Ireland's defeat of the Pacific Islands.
Big guns Brian O'Driscoll, Gordon D'Arcy, Denis Hickie, Shane Horgan, Malcolm O'Kelly, Luke Fitzgerald all return while also included the squad is ex-Ulster prop Ronan McCormack, who is joined by fellow Ireland A players Kieran Lewis, Keith Gleeson, Trevor Hogan and Rob Kearney.
The match was last night declared an all-ticket game, with less than 500 tickets remaining.
ULSTER SQUAD: (Backs) Paul Marshall; Kieran Campbell; Isaac Boss; David Humphreys; Adam Larkin; Paddy Wallace; Kevin Maggs; Paul Steinmetz; Paul McKenzie; Mark Bartholomeusz; Bryn Cunningham; Scott Young (Forwards): Simon Best; Bryan Young; Justin Fitzpatrick; Rory Best; Paul Shields; Justin Harrison; Matt McCullough; Tim Barker; Roger Wilson; Neil Best; Kieron Dawson; Stephen Ferris; Neil McMillan
LEINSTER SQUAD: (Backs): Chris Whitaker, Guy Easterby, Andrew Dunne, Christian Warner, Gordon D'Arcy, Brian O'Driscoll, Kieran Lewis, Shane Horgan, Denis Hickie, Luke Fitzgerald, Girvan Dempsey, Rob Kearney (Forwards): Ronan McCormack, Reggie Corrigan, Brian Blaney, Harry Vermaas, Fosi Pala'amo, Trevor Hogan, Malcolm O'Kelly, Owen Finegan, Cameron Jowitt, Stephen Keogh, Keith Gleeson, Jamie Heaslip.