Munster will be going for a clean sweep of eight successive wins over Welsh regions this season when they travel to Scarlets in the RaboDirect Pro 12 on Saturday.
The hosts go into the clash at Parc y Scarlets having won their last two matches, but have not won three in a row in the tournament since last April.
Donncha O'Callaghan joins Donnacha Ryan in the second-row for the trip to Llanelli as one of eight changes to the Munster side that beat Ospreys last weekend with James Coughlan captaining the team.
Wales centre Jonathan Davies returns to action for the Scarlets. Davies' inclusion is head coach Simon Easterby's only change to the side that triumphed over Edinburgh last Saturday.
Second-placed Leinster take on Glasgow having not tasted defeat at the RDS in any tournament since last March.
Boss Matt O'Connor has made ten changes in personnel to the 15 selected last Thursday away to the Blues with players released from the Irish set up once again included from the start, while another two are named amongst the replacements.
Warriors' record breaking sequence of seven successive away victories in the PRO12 ended on Sunday with their narrow 23-24 defeat at the Dragons, but they will be determined to get back to winning ways with a tough trip to Ireland.
Full-back Peter Murchie makes his long-awaited return from injury on Saturday as his side take on Leinster.
The 28-year-old has been out of action since October with a dislocated shoulder but returns for the trip to face the champions at the RDS.
Connacht will be aiming for a third straight win for the first time in a year when they entertain Treviso at the Sportsground.
Coach Pat Lam has made three personnel changes while scrum-half Kieran Marmion is in line to earn his 50th cap.
The Italian side have a poor away record though, having not won on the road in the tournament since round 22 last season.
Azzurri flankers Robert Barbieri, Paul Derbyshire and Manoa Vosawai, prop Lorenzo Cittadini, winger Angelo Esposito, centre Alberto Sgarbi and lock Antonio Pavanello return for the game.
Zebre have the opportunity to achieve a Pro12 double when they face Cardiff Blues at the Stadio XXV Aprile.
Flanker Rory Watts-Jones returns to the starting XV. He is one of three changes to the starting side as the Blues look for a return to winning ways.
The Italian outfit currently sit at the bottom of the table, but they beat the Blues 30-25 at the Arms Park in round three and take on a side which has failed to win an away game in the competition this season.
Zebre will hand a Rabo debut to young South African flanker Abraham Steyn, who joins Samuela Vunisa and Filippo Ferrarini in Saturday's back-row.