The RaboDirect Pro12 season enters a fifth week on Friday with three matches - the Ospreys and Dragons both on home soil while Connact make a trip across the continent.
Ospreys, who boast an unbeaten record in the 2013/14 campaign, host Ulster at the Liberty Stadium.
Ospreys coach Steve Tandy has made five changes to the side which strode over Connacht 43-26 last time out. There is a new centre partnership which sees Andrew Bishop and Ashley Beck link up at the expense of Ben John and Jonathan Spratt, while up front, prop Ryan Bevington and flankers Tyler Ardron and Joe Bearman are all handed starts.
Ulster meanwhile, will be without British and Irish Lion Tommy Bowe, who sustained a dead leg during the bonus-point victory against Treviso in round four.
Ireland winger Andrew Trimble will deputise on the right, while Nick Williams, Duncan Fitzpatrick and captain Johann Muller all return to Mark Anscombe's pack.
Friday's showdown could see Ospreys extend their 10-game winning streak but if last season's meetings between the pair are anything to go by, there will be little between the sides.
Both fixtures were narrowly edged by the away side with the overall points scored over two games giving the Ospreys a 29-28 advantage. Five of the last six encounters have seen the losing side take away a bonus point.
Newport Gwent Dragons have been boosted by the return of Lions star Toby Faletau as they prepare to host Zebre at Rodney Parade.
Faletau will don the No 8 jersey and joins Netani Talei and Lewis Evans in an all-new Dragons back row as Darren Edwards rings the changes to the side which lost 23-9 to Munster last weekend.
Zebre will look to extend their point-scoring run to three matches as they travel to Wales for the second time in three weeks after registering their first Pro12 victory against Cardiff Blues last month.
Italy international centre Gonzalo Garcia returns to the touring party while winger Dion Berryman and hooker Davide Giazzon are both included, with Leonardo Sarto and Andrea Manici left out of the 23-man squad.
Also on Friday, Connacht head coach Pat Lam will field a much-changed starting XI as the Irishmen travel to Treviso in search of only their second victory of the season.
Since their opening day victory against Zebre, Connacht have endured a worrying run which has forced South African Lam to make nine changes to the side which suffered a 43-26 drubbing at the hand of Ospreys last time out.
Lock Aly Muldowney made a strong impression from the bench at the Sportsground in round four and gets the nod in the pack, as do props Rodney Ah You and Ronan Loughney and No 8 George Naoupu; while Tiernan O'Halloran, Fionn Carr, Eoin Griffin and Dan Parks all start in the backs alongside Paul O'Donohoe, who dons the No 9 jersey for the first time this season.
There are significantly less changes for Treviso, however, with Alberto Di Bernardo named at fly-half and Brendan Williams taking the full-back berth, Robert Barbieri returns to the engine room at No 8.
Both sides will be eager to add a second victory to their tally but Connacht face a stiff challenge with the hosts having lost just one of their last eight fixtures at the Stadio Monigo.