Ulster have made four personnel and two positional switches for tomorrow’s Heineken Cup match against Castres Olympique at Stade Pierre-Antoine.

Mark Anscombe has opted to partner Paul Marshall with Ruan Pienaar at half back for the crunch fixture. Pienaar takes over at out half with Paddy Jackson named among the replacements.

With Jared Payne injured, Ireland winger Craig Gilroy is deployed at fullback, allowing Michael Allen to be called up to the left wing for his first European start. Andrew Trimble lines up on the opposite flank, while Paddy Wallace and Darren Cave continue their midfield partnership.

Up front, Neil McComb will also make his first European start after being named at lock in place of Iain Henderson, who drops to the bench. McComb is partnered in the second row by Lewis Stevenson, who was one of 11 Ulstermen to receive a call up to the extended Ireland training squad on Thursday.

There are no changes to the front row which includes Rory Best, John Afoa and Tom Court, who has collected Man of the Match awards in two of his last three starts.

Nick Williams, who is out for eight weeks with a medial ligament knee injury, has an able replacement at number 8 in the form of Roger Wilson. Captain Chris Henry and the in-form South African Robbie Diack are the other loose forwards.

Ulster team to play Castres Olympique in the Heineken Cup Pool 4, Saturday at 1.35pm:

(15-9): C Gilroy; A Trimble, D Cave, P Wallace, M Allen; R Pienaar, P Marshall; (1-8): T Court, R Best, J Afoa, L Stevenson, N McComb, R Diack, C Henry (capt), R Wilson;

Replacements (16-23): R Herring, C Black, D Fitzpatrick, I Henderson, M McComish, M Heaney, P Jackson, C Cochrane.