Edinburgh can do their Scottish neighbours Glasgow Warriors a favour if they can defeat Ulster, however their record against the Ulstermen is not great.
Meanwhile, the play-off chasing Ospreys and Scarlets must both be looking to come away with maximum points from opponents who are sitting at the wrong end of the league table.
Table toppers Glasgow are not in action until Saturday, and are the only one of the potential play-off teams to face another side from the top half of the table when the visit Leinster at the RDS.
Munster will also be looking for maximum points this weekend if they are to make a final charge for the knockout stages. But they face an in-form Connacht team who will be hunting for a prized interprovincial derby win in Cork.
With just two points separating the top three teams in the table - and it is even closer for the final semi-final spot - there is definitely all to play for still as the PRO12 enters its closing stages.
RABODIRECT PRO12 - ROUND 18 FIXTURES:
Friday, March 22 -
Zebre (12th) v Scarlets (4th), Stadio XXV Aprile, 7pm (live SportItalia 2)
Ospreys (5th) v Newport Gwent Dragons (11th), Liberty Stadium, 7.05pm (live BBC 2 Wales)
Edinburgh (10th) v ULSTER (2nd), Murrayfield, 7.30pm (live BBC NI Sport website/red button)
Saturday, March 23 -
MUNSTER (6th) v CONNACHT (9th), Musgrave Park, 5.45pm (live TG4)
Benetton Treviso (7th) v Cardiff Blues (8th), Stadio di Monigo, 7.30pm (live SportItalia 2/S4C)
LEINSTER (3rd) v Glasgow Warriors (1st), the RDS, 7.45pm (live RTÉ Two/BBC ALBA)