Leinster v Castres team news: Seán O'Brien will make his first Heineken Cup start for Leinster tomorrow afternoon in place of the injured Shane Jennings. Jennings has failed to overcome a knee injury and will remain on the sidelines for Castres' visit to Dublin 4.
O'Brien, a try-scorer against the Dragons in the Magners League last weekend, will start at openside flanker alongside Rocky Elsom and Jamie Heaslip in the Leinster back row.
Coach Michael Cheika has made four changes from last Saturday's team with the fit-again CJ van der Linde coming back into the side while the rested trio of Luke Fitzgerald, Rob Kearney and Heaslip also return.
On the bench, the returning David Holwell continues to provide cover for Jonathan Sexton while Stephen Keogh is selected ahead of Cameron Jowitt.
Leinster go into tomorrow's clash, the first of back-to-back meetings with the French side, seeking to rubber-stamp their position at the top of Pool Two.
With bonus point wins over Edinburgh and Wasps already under their belts the province lead with a maximum haul, six clear of their nearest challengers.
Leinster: G Dempsey; S Horgan, B O'Driscoll, L Fitzgerald, R Kearney; J Sexton, C Whitaker; S Wright, B Jackman, CJ van der Linde; D Toner, M O'Kelly; R Elsom, S O'Brien, J Heaslip. Replacements: B Blaney, C Healy, T Hogan, Stephen Keogh, C Keane, D Holwell, Simon Keogh.
