Team news: Rory Best has been included in Mark McCall's squad for Ulster's trip to Cardiff on Friday night but a final decision on his availability will be not be made until later in the week
The Ireland hooker picked up a neck injury against Borders last weekend and while scans revealed there was no long-term damage he remains a doubt as Ulster attempt to bridge the gap on table-toppers Leinster.
Paddy Wallace is also a concern but Neil McMillan and Paul Steinmetz return to the fold following their enforced absences.
Ulster are currently second in the league behind Leinster, who lead with 55 points. Cardiff could come right back into contention with a win at the Arms Park as they trail Ulster by just six points and have two games in hand.
Ulster squad: Kieran Campbell; Isaac Boss; David Humphreys; Paddy Wallace; Paul Steinmetz; Andrew Trimble; Paul McKenzie; Andrew Maxwell; Bryn Cunningham; Tommy Bowe; Simon Best (c); Bryan Young; Justin Fitzpatrick; Rory Best; Paul Shields; Neil Brady; Justin Harrison; Ryan Caldwell; Tim Barker; Roger Wilson; Neil Best; Neil McMillan; Stephen Ferris