Ulster look set to be without British and Irish Lions wing Tommy Bowe for up to six weeks due to a groin injury.
The injury means Bowe will miss the Belfast team's back-to-back Heineken Cup matches against Treviso as well as the Pro12 fixtures over the festive season.
Bowe suffered a groin injury while on international duty with Ireland. A scan on Tuesday revealed that he has suffered a muscle tear and that he will be out of rugby for between four and six weeks meaning he could also miss Ulster's remaining pool games at home to Montpellier and away to Leicester.
There is some good news for Ulster fans however as captain Johann Muller has returned to training and will be available for selection this weekend.
Paddy Wallace has also returned to full training following the ACL injury that he sustained in February and should play this weekend.
Full-back Jared Payne continues his recovery from a groin injury. He will be assessed later in the week with a view to his participation against Treviso.
Prop Paddy McAllister has been ruled out with a torn hamstring while Rory Best fractured his arm against the All Blacks and will not be available before the New Year.