With Cardiff Blues, the Newport Gwent Dragons and the Scarlets all within one point of each other, and Connacht 10 points adrift, it will be a testing time for the Welsh regions as they head into the last few games of the season.
Two of the regions, the Blues and the Dragons, clash in a midweek fixture which could be decisive in the matter of league points, before the penultimate round.
Round 17 opens on Friday night with Ulster's visit to Connacht. Connacht have already beaten the other two Irish provinces at the Sportsground this season, so victory this Friday would make it a clean sweep over their fellow countrymen.
Also on Friday night, Heineken Cup finalists Leinster welcome the Scarlets to the RDS, with the Welshmen looking for points to avoid the play-off place.
There is a return to Saturday rugby at Murrayfield when Edinburgh host the Dragons, with Andy Robinson's men aiming for the highest Scottish finish in the Magners League, whilst the Dragons are another team in the mix for the Heineken Cup play-off spot.
The round wraps up on Sunday with a televised 'double header'.
The Ospreys will welcome Glasgow Warriors to the Liberty Stadium, a venue where the visitors have never won, and the two defeated Heineken Cup semi-finalists, Cardiff Blues and Munster, are scheduled to meet at the Arms Park.
The Blues must be hoping that Munster, having already secured the title, will let slip the form that has seen them win their last nine games against Welsh regions.
MAGNERS LEAGUE - ROUND 17 FIXTURES:
ROUND 15 (Refixed game):
Wednesday, May 6 -
Cardiff Blues v Newport Gwent Dragons, Arms Park, 7.05pm (live BBC Wales)
Friday, May 8 -
CONNACHT v ULSTER, The Sportsground, 7pm
LEINSTER v Scarlets, The RDS, 7.45pm (live Setanta Sports Ireland/BBC Wales)
Saturday, May 9 -
Edinburgh v Newport Gwent Dragons, Murrayfield, 2.30pm
Sunday, May 10 -
Ospreys v Glasgow Warriors, Liberty Stadium, 2.35pm (live S4C)
Cardiff Blues v MUNSTER, Arms Park, 4.35pm (live Setanta Sports Ireland/Setanta Sports 1/S4C)