The two sides have met on six previous occasions in Celtic League and Celtic Cup with Ulster winning just once: 31-19 at Ravenhill on 13 February 2004. Ospreys give a first regional start to fly-half prodigy James Hook, who replaces Shaun Connor in Swansea. It is one of three changes to a strong side, Lee Beach in for Richie Pugh and Barry Williams - in his last appearance as skipper - for Huw Bennett.
Loose head Justin Fitzpatrick makes a rare start as Ulster go in search of their first Celtic League title. He replaces skipper Simon Best (ankle), Bryn Young moving to tight-head, James Topping and Rod Moore making the bench.
The 32-year-old Fitzpatrick has not featured since his return from Castres at the start of the season, but was called up after Best fractured his ankle in last week's draw with the Scarlets.
Ospreys: Gavin Henson; Jonathan Vaughton, Sonny Parker, Andrew Bishop, Shane Williams; James Hook, Jason Spice; Duncan Jones, Barry Williams (capt), Adam Jones, Alun Wyn Jones, Ian Evans, Jonathan Thomas, Lee Beach, Andrew Lloyd
Replacements: Richard Hibbard, Andrew Millward, Paul James, Andrew Newman, Richard Pugh, Matthew Jones, Stefan Terblanche
Ulster: B Cunningham; T Bowe, A Trimble, P Wallace, A Maxwell; D Humphreys, I Boss; J Fitzpatrick, R Best, B Young, J Harrison, M McCullough, N Best, S Ferris, R Wilson
Replacements: N Brady, R Moore, R Caldwell, N McMillan, K Campbell, J Bell, J Topping
Referee: David Changleng (SRU)