Ross was replaced by former Castleknock College tighthead prop Martin Moore who was one of three players - alongside Jimmy Gopperth and Brendan Macken - to make their first European appearances for the province.
Brian O'Driscoll (calf strain) continues to respond well to treatment and it is hoped that he will resume some on-field activity later this week with a decision on his availability set to be made later in the week. Lote Tuqiri (hamstring) is unlikely to feature as he continues his rehabilitation.
Commenting on the injuries to Ross and O'Driscoll, Leinster scrum coach Greg Feek said today: "We're going to see how he (Ross) goes. He's a pretty important cog in the wheel for us, so we'll give it as long as it takes to come right.
"If he's not available then we'll have to deal with that, but obviously it's Heineken Cup week and Castres is not easy opposition.
"Brian's progressing and working through his calf and that, so he's probably a wee bit away yet."
Meanwhile, Leinster are set to be boosted by the inclusion of South African international Zane Kirchner who arrived in Dublin last week having performed strongly in the Rugby Championship in recent months.
There is an outside chance that Shane Jennings, who suffered a fractured bone in his hand away to Glasgow Warriors last month, could also feature as he is set to return to contact training this week.
Next Saturday's game could mark a double milestone for the province as both Fergus McFadden and Kevin McLaughlin are now level on 99 provincial appearances and are set to become the 23rd and 24th Leinster players respectively to reach the century landmark.
Sean O'Brien, a try-scoring man-of-the-match in the 19-9 defeat of the Ospreys, will be making his 85th Leinster appearance next time out.
Ticket sales for Leinster v Castres at the RDS have passed the 17,400 mark. Tickets are on sale online here and are also available from the Leinster Rugby Store (Donnybrook), Spar (Donnybrook) and Ticketmaster outlets nationwide.