Ulster v Llanelli Scarlets: This is a pivotal match for tonight's combatants. The winner can kick on in pursuit of Celtic League table-toppers while the loser will be relegated to the periphery. Llanelli have two games in hand but to realise that advantage they have to continue winning.

Ulster, in fourth place, are three points ahead of tonight's visitors having played a couple of matches more. The significance of this clash is not lost on Scarlets director of rugby Gareth Jenkins.

"This weekend's fixture is a huge one for us and there's no room for an ounce of complacency in our game. We need to refocus out of Europe and into the Celtic League. Away fixtures in Ireland are among the most difficult in the league, but in order to win the tournament you need to be able to travel away and bring home a result," he said.

Llanelli produced a gallant performance in defeat to Toulouse during last weekend's Heineken European Cup action, causing the French side plenty of problems. Daffyd James retains the captaincy in the absence of Ireland's Simon Easterby while Welsh commitments also deprive the visitors of Mark Jones and Dwayne Peel.

James switches to centre with Tal Selley and Garan Evans on the wings. Lee Byrne misses the match with a chest infection. Gareth Bowen is named ahead of Mike Hercus at outhalf with the latter dropping to the bench. Clive Stuart-Smith starts at scrumhalf while Scarlets Academy scrumhalf Liam Davies finds himself in the match squad.

In the front row, Martyn Madden switches to tighthead prop to facilitate Craig Dunlea's inclusion on the other side of the scrum. John Davies is named on the bench. Adam Jones is struggling with injury so former Tongan captain Inoke Afeaki and Springbok Hottie Louw form the secondrow pairing.

Ulster coach Mark McCall is without five players, who are with the national squad, and has made three changes to the side that beat Treviso in Italy last week. Bryn Cunningham returns at fullback - Tommy Bowe is with Ireland - and Johnny Bell is named at outside centre in place of Andrew Trimble. The only change in personnel in the pack sees Neil McMillan return to the starting line-up.

Promising young underage international Stephen Ferris switches to the blindside flank with Neil Best among the replacements having spent the week with the Ireland squad. Ulster will lose a little bit of the cutting edge in the absence of Trimble and Bowe, not to mention the direction and composure David Humphreys brings to outhalf.

This is a very tough match for Ulster as they appear to be the more depleted side. Previous encounters between these teams have gone the way of the home team but unless several Ulster players raise performance levels this match could buck the trend.

ULSTER: B Cunningham; J Topping, J Bell, P Steinmetz, A Maxwell; A Larkin, I Boss; J Fitzpatrick, N Brady, B Young; J Harrison (capt), M McCullough; S Ferris, N McMillan, R Wilson. Replacements: P Shields, R Moore, R Frost, N Best, K Campbell, P Wallace, T Howe.

LLANELLI SCARLETS: B Davies; T Selley, D James (capt), R King, G Evans; G Bowen, C Stuart-Smith; C Dunlea, M Rees, M Madden; I Afeaki, H Louw; D Jones, G Thomas, Alix Popham. Replacements: J Davies, A Gravelle, V Cooper, G Quinnell, L Davies, M Hercus, G Evans.

Referee: Rob Dickson (Scotland).

Recent meetings: February 2004 (CL) at Ravenhill: Ulster 10 Llanelli Scarlets 9; May 2004 (CL) at Stradey Park: Llanelli Scarlets 23 Ulster 16; November 2004 (CL) at Stradey Park: Llanelli Scarlets 22 Ulster 9; April 2005 (CL) at Ravenhill: Ulster 16 Llanelli Scarlets 3.

Leading points scorers: Ulster - David Humphreys 130. Llanelli - Mike Hercus 42.

Leading try scorers: Ulster - Tommy Bowe 5. Llanelli - Barry Davies, Lee Byrne, Matthew Watkins 3 each.