OSPREYS (2nd) v ULSTER (5th), Liberty Stadium, 7.05pm (live BBC 2 Northern Ireland/BBC 2 Wales)
Team News: Ireland winger Andrew Trimble has recovered from injury to be included in the Ulster team to face the Ospreys in Swansea on Friday night.
Trimble underwent surgery on an injured finger three weeks ago and starts on the right wing in place of Tommy Bowe, who has failed to recover from the dead leg he sustained during the bonus point win over Benetton Treviso at Ravenhill last weekend.
Ulster head coach Mark Anscombe has made four changes in total. Captain Johann Muller returns in the second row, while Declan Fitzpatrick is selected at tighthead prop having recovered from the injury that he picked up against Connacht in Galway.
In the only other change, Nick Williams, who signed a new two-year deal with the province this week, starts at number 8 with Roger Wilson moving to the replacements bench.
Young Ireland international Stuart Olding is also set fo bench duty and is in line to make his first appearance of the season if called upon.
Meanwhile, the Ospreys boast quite a settled side as they look to make it back-to-back victories over Irish opposition - they ran out 43-26 bonus point winners at Connacht in the previous round.
Head coach Steve Tandy has rotated some of his combinations for the visit of Ulster, with Andrew Bishop and Ashley Beck returning in the centre at the expense of Ben John and Jonathan Spratt.
Adam Jones is the only survivor in the front row as Ryan Bevington and Richard Hibbard come back in, while captain Alun Wyn Jones - a late try scorer against Connacht and one of five 2013 Lions in the starting pack - is set to make his 150th appearance for the Welsh region.
At the opposite end of the scale, there is a first Ospreys start for Canadian international Tyler Ardron at blindside flanker and Joe Bearman's selection at number 8 is the sixth and final change.
OSPREYS: Richard Fussell; Jeff Hassler, Andrew Bishop, Ashley Beck, Eli Walker; Dan Biggar, Tito Tebaldi; Ryan Bevington, Richard Hibbard, Adam Jones, Alun Wyn Jones (capt), Ian Evans, Tyler Ardron, Justin Tipuric, Joe Bearman.
Replacements: Scott Baldwin, Duncan Jones, Aaron Jarvis, James King, Sam Lewis, Tom Habberfield, Matthew Morgan, Ben John.
ULSTER: Craig Gilroy; Andrew Trimble, Jared Payne, Luke Marshall, Michael Allen; Paddy Jackson, Paul Marshall; Tom Court, Rory Best, Declan Fitzpatrick, Johann Muller (capt), Dan Tuohy, Robbie Diack, Chris Henry, Nick Williams.
Replacements: Rob Herring, Callum Black, Bronson Ross, Iain Henderson, Roger Wilson, Michael Heaney, Stuart Olding, Darren Cave.
Referee: Peter Fitzgibbon (Ireland)
Assistant Referees: Jon Mason, Wayne Davies (both Wales)
Television Match Official: Derek Bevan (Wales)
Match Odds (Paddy Power): Ospreys to win: 1/2; Draw: 22/1; Ulster to win: 13/8
Pre-Match Quotes: Michael Allen (Ulster) - "It's going to be very difficult and (the Liberty Stadium) is a tough place to go. We played terribly there last year but won and that's something we would probably take again against a team with so many Welsh internationals and Lions players.
"There's no better test than to play against these guys and I'm really excited about it.
"The last two weeks it was a case of my place being on the line and if I didn't perform I was going to be shipped out, simple as that.
"Hopefully now I've managed to put a small bit of doubt in Mark's mind when it comes to taking me out but I'll need to keep this up.
"Obviously Craig (Gilroy) and Andrew are internationals and Tommy's a Lion so I know it's never going to be easy to get into this team.
"Playing Leicester next week (in the Heineken Cup) would be fantastic. Obviously it's hard to leave the other guys out because they have the experience, but I'll be trying to put my hand up for a place."
Steve Tandy (Ospreys) - "We are really pleased to be where we are in the table four weeks in and after three games on the road, but we aren't going to allow ourselves to get carried away.
"There's plenty of room for improvement in a few areas of our game, and we are going into a tough run of fixtures where we are going to have to move up several gears if we are going to keep building momentum.
"Ulster on Friday night is as difficult as it gets. They've got a strong squad with world class players in there, Lions, All Blacks and Springboks, and as they've shown over the last two seasons in getting to Heineken and PRO12 finals, they can beat anyone so we are going to have to be at our very best.
"It should be a cracking contest, and is the first of two home games on the bounce against quality opposition with Leinster at the Liberty next weekend.
"This is what we've been building towards in the opening weeks of the season and it's a period that any rugby fan will be excited about."
Top Scorers - 2013/14 RaboDirect PRO12: Ospreys - Points: Dan Biggar 63; Tries: Eli Walker 3; Ulster - Points: Paddy Jackson 35; Tries: Michael Allen 3
RECENT LEAGUE MEETINGS:
Friday, September 3, 2010 - Ulster 27 Ospreys 26, Ravenhill
Sunday, February 13, 2011 - Ospreys 23 Ulster 22, Liberty Stadium
Sunday, September 25, 2011 - Ospreys 32 Ulster 14, Liberty Stadium
Friday, February 24, 2012 - Ulster 15 Ospreys 14, Ravenhill
Saturday, September 8, 2012 - Ospreys 13 Ulster 16, Liberty Stadium
Friday, February 8, 2013 - Ulster 12 Ospreys 16, Ravenhill
- The Ospreys are one of just two unbeaten teams in the RaboDirect PRO12 this year, and have won their last 10 home games at the Liberty Stadium in the league since Glasgow Warriors won there just over 12 months ago
- Just one Irish province has won in Swansea since April 2011: Ulster themselves, 16-13, in September 2012
- Ulster have now won their last two fixtures, against Connacht and Benetton Treviso, to end a three-match losing run
- The Ulstermen have already been defeated by a Welsh region this season, going down 15-8 to the Newport Gwent Dragons at Rodney Parade in round 1
- Both of last season's fixtures were narrowly won by the away side on the day with the overall points scored in the two games being Ospreys 29 Ulster 28
- Five of the last six encounters have seen the losing side gain a bonus point