Published Thursday, 11 October 2012
Stephen Ferris in training ahead of Ulster's match against Connacht. (© Pacemaker)
Ferris came off the pitch during Thursday's training session due to back pain.
Coach Mark Anscombe told UTV Sport: "It was just a precaution bringing him off because of a back spasm.
"He should be ok for tomorrow, he got it treated straight away."
The Ulster starting 15 for the clash against the French side has been announced.
Nick Williams has been ruled out for the match. He failed to recover from a rib injury picked up playing against Connacht last weekend.
His replacement is 20-year-old back row Iain Henderson, who is making his home debut.
The match will be his fourth appearance for Ulster, his first in the Heineken Cup.
On Wednesday, it was revealed that the Ireland U20 star had signed his first full contract, keeping him at the club until June 2015.
He said: "I can't wait. I've been watching games at Ravenhill since I was a kid and I'm really looking forward to pulling on the white jersey and experiencing the atmosphere as a player.
"My first aim for the season was to be involved in a few PRO12 games but with the few injuries that we have in the back row, I've been given an opportunity and I have to try and grab it with both hands."
Henderson's inclusion at blindside flanker will mean Stephen Ferris, if fit to play, switches to the back of the scrum.
He continued: "Castres are a very physical team but they also throw the ball wide and have an expansive kicking game. That should make for a tough, but entertaining game. We'll have to work really hard to nullify their threats."
The rest of the team is unchanged from Friday's victory over Connacht.
Ruan Pienaar returned from Rugby Championship duty with South Africa earlier this week. He has been named in place of Michael Heaney in the replacements bench.
Ulster XV to face Castres Olympique on Friday at Ravenhill, kick-off 8.00pm.
(15-9): J Payne; T Bowe, D Cave, P Wallace, A Trimble; P Jackson, P Marshall;
(1-8): T Court, R Best, J Afoa, J Muller (c), D Tuohy, I Henderson, C Henry, S Ferris;
(16-23): R Herring, C Black, A Macklin, L Stevenson, M McComish, R Pienaar, L Marshall, C Gilroy.