Sean O'Brien takes on Saracens in their October Heineken Cup clash

Sean O’Brien will step into the No 8 shirt vacated by the injured Jamie Heaslip when Leinster entertain Saracens in Saturday’s round 5 Heineken Cup clash. Having missed last weekend’s Magners League victory over the Ospreys due to a nasty cut above his eye, the 23-year-old was this week named the Bank of Ireland Player of the Month thanks to his recent  good form, and he must be pushing for a place in Ireland’s back row for the upcoming RBS Six Nations.

Leo Cullen captains the home side and is joined by Nathan Hines in the second row while Devin Toner drops to the bench. Leinster are also without Rob Kearney and have opted for Isa Nacewa at full-back, while Fergus McFadden and Shane Horgan are on the wings, leaving Luke Fitzgerald on the bench.

The Londoners have made four changes from the team that beat London Irish last week, with Ernst Joubert, Rhys Gill, Nils Mordt and Hugh Vyvyan all coming into the side. Gavin Henson is named on the bench having been registered to play in the Heineken Cup this week, and Owen Farrell and Richard Wigglesworth make up the half-back partnership.

Leinster have cruised through the pool stage so far and are currently 5 points clear at the top of the table, but while Saracens have lost three of their European games so far, they showed what they are capable of by beating Racing Metro at the Stade Yves du Manoir in December, and will be looking to spoil Leinster’s party.

But beating Leinster at this stage of the Heineken Cup in their own back yard will be no mean feat, and it would be a shock for them to slip up at this stage.

Leinster: I Nacewa; S Horgan, B O’Driscoll, Gordon D’Arcy, F McFadden; J Sexton, E Reddan; C Healy, R Strauss, M Ross; L Cullen (capt), N Hines; D Ryan, S Jennings, S O’Brien.

Replacements: J Harris-Wright, H van der Merwe, C Newland, D Toner, K McLaughlin, I Boss, I Madigan, L Fitzgerald.

Saracens: N Mordt, D Strettle, M Tagicakibau, B Barritt, J Short, O Farrell, R Wigglesworth, R Gill, S Brits, C Nieto, S Borthwick, H Vyvyan, K Brown, A Saull, E Joubert.

Replacements: J George, J Saunders, P Du Plessis, H Smith, J Melck, N de Kock, G Henson, N Cato

Referee: Romain Poite (France)

Click here to see the video of Shane Jennings previewing the game