Celtic League/Cardiff Blues v Ulster, The Arms Park, 7.05: Neath-Swansea Ospreys have secured the Celtic League title so attention now turns to who will fill the other top seven places and automatically go through to the quarter-finals of the end-of-season Celtic Cup. The Ospreys, Munster and Leinster have secured their places in the knock-out competition but only The Ospreys and Munster are assured of a home draw.

Tenth-placed Cardiff Blues and seventh-placed Ulster meet tonight in the Arms Park with the visitors ideally placed to clinch one of the slots and at the same time do Connacht a huge favour.

Ulster coach Mark McCall has had to make a late change with outhalf David Humphreys forced out with a hamstring strain. Humphreys will be replaced by Paddy Wallace, and Adam Larkin is drafted on to the bench.

Otherwise, McCall has named an unchanged backline from the team that defeated The Borders last week. But there are changes up front. Rod Moore is drafted in as tighthead prop with Simon Best moving to loosehead and Ronan McCormack dropping to the bench. Gavin Pfister replaces the injured Neil Best while Gary Longwell will win his 150th cap for the province.

Cardiff have named Wales under-21 star Chris Czekai in the starting line-up in what will be his debut at this level. The 6ft 2in winger, who scored five tries in as many matches for the Welsh Grand Slam winning under-21s will be one of the eye-catching figures on view.

Rhys Williams also returns for Cardiff after shaking off a leg injury. He will play at outside centre alongside Tom Shanklin with Nick Macleod continuing at fullback. Cardiff are buoyed by the news that tighthead Gethin Jenkins has passed a fitness test.

With just three matches remaining for McCall's team, it is crucial they secure position now rather than allowing it to hinge on the final match. Without Humphreys, however, the advantage lies with the home side.

CARDIFF BLUES: N Macleod; C Czekaj, R Williams, T Shanklin, C Morgan; N Robinson, R Powell; J Yapp, G Williams, G Jenkins, C Quinnell, R Sidoli, R Sowden-Taylor, K Schubert, M Williams (captain). Replacements: B Evans, R Thomas, N Budgett, N Thomas, M Molitika, D Dewdney, T Davies/J Vaughton.

ULSTER: B Cunningham; T Bowe, K Maggs, P Steinmetz, T Howe; P Wallace, K Campbell; S Best, P Shields, R Moore, G Longwell, M McCullough, A Ward (capt), G Pfister, S Wilson. Replacements: N Brady, R McCormick, R Frost, N Doak, C Feather, A Larkin, S Young.

Referee: D Changleng (Scotland).

Verdict: Home win.