A win for Ulster will put them well clear at the top of the table, anything less and they have to start looking over their shoulders at what their nearest rivals are doing.
Glasgow are the only one of the top three playing away from home, and carry the added disadvantage of having won one game less than the two teams who are above them, so must go all out for a win and see what happens elsewhere to secure home advantage in the knock-out stages.
The pick of the final round of this RaboDirect PRO12 campaign must be the repeat of last season's final between hosts Leinster and 2012 champions Ospreys at the RDS.
Leinster have already secured a play-off spot, the question is whether it will be home or away. The Ospreys must win and hope that other results go their way, if they are to snatch the fourth and final play-off place from Welsh neighbours, the Scarlets.
The Scarlets, four points clear of the Ospreys and one win to the better of their rivals, have the added advantage of playing their last regular season game at home, but even so must be wary as they lost to Benetton Treviso in the reverse of this fixture earlier in the season.
Comes 10pm on Friday night, all the questions should answered.
Friday, May 3 -
CONNACHT (8th) v Glasgow Warriors (3rd), the Sportsground, 7.45pm (live RTÉ Two/BBC ALBA)
Edinburgh (10th) v Newport Gwent Dragons (11th), Murrayfield, 7.45pm
LEINSTER (2nd) v Ospreys (5th), the RDS, 7.45pm (live TG4/S4C)
Scarlets (4th) v Benetton Treviso (7th), Parc y Scarlets, 7.45pm (live BBC 2 Wales)
ULSTER (1st) v Cardiff Blues (9th), Ravenhill, 7.45pm (live BBC 2 Northern Ireland)
Zebre (12th) v MUNSTER (6th), Stadio XXV Aprile, 7.45pm local time/6.45pm Irish time (live SportItalia 2)