Leinster v Ospreys, RDS Arena, kick-off: 7.35pm
Johnny Sexton and Dan Biggar make their first starts of the campaign, the simultaneous return of the Test fly halves guaranteeing a liberal sprinkling of stardust for one of the biggest duels anywhere in Europe this weekend.
Alun-Wyn Jones captains the Ospreys in his 200th match for the leaders, one of twelve internationals in a starting line-up containing just three uncapped players – Sam Davies, Ben John and Lloyd Ashley.
Fasten your seat belts…
Glasgow Warriors v Ulster, Scotstoun Stadium, kick-off: 7.35pm
Ruan Pienaar will consider it high time that Glasgow belonged to Ulster again. They haven’t won there in the Guinness PRO12 since the Springbok scrum-half produced a last-minute try in scoring all 22 points at Firhill on March 25, 2011.
The Warriors, with Finn Russell back at ten and teenager Lewis Wynne in the back row, have more than doubled their crowd since then and the vast majority of a sell-out Scotstoun will want to see another home win.
Benetton Treviso v Newport Gwent Dragons, Stadio Monigo, kick-off 8.05 pm
Treviso broke even at home last season against Welsh opposition. Four close encounters brought wins over Cardiff Blues (13-7) and the Dragons (19-17) in between narrow defeats against Ospreys (22-25) and Scarlets (20-22).
Dragons, captained by 21-year-old Wales wing Hallam Amos, haven’t won away in the PRO12 for more than 18 months, since March 28, 2015 when they won 32-17 at Treviso.
Munster v Edinburgh, Thomond Park, kick-off: 3pm
When Edinburgh last ventured into Limerick’s citadel, two years ago, they had the effrontery to make a piece of history Munster could have done without.
Scotland’s capital team inflicted an unprecedented third straight defeat at Thomond Park, Jack Cuthbert’s try and Tom Heathcote’s penalty hat-trick edged the Scots home, 14-13.
Zebre v Cardiff Blues, Stadio Sergio Lanfranchi, kick-off: 5.05pm
The Blues need only recall last season’s matches against the Italians for a classic example of why someone once called it a funny old game. They hit Zebre with an avalanche of eleven tries at BT Sport Cardiff Arms Park this time last year, then lost the return the following month, 26-15.
Against opponents denied the prospect of a win over Connacht last week because of a thunderstorm, the unbeaten Blues must avoid lightning striking place at the same place.
Scarlets v Connacht, Parc y Scarlets, kick-off: 7.35pm
The ‘west-is-best’ mantra as coined by the late Ray Gravell of Wales and Lions’ fame has taken a battering over the last three weeks.
Between them, the west Walians and Ireland’s western province have managed just five tries so far this season, one fewer than when they last met, in Galway last January.
Connacht out-tried the Scarlets 4-2 and won 30-17, avenging a 19-21 loss in Llanelli a few weeks earlier.