Both the Blues and Ospreys are on home soil as they take on Ulster and Aironi respectively, while the seventh-placed Scarlets travel to Dublin to face European Champions Leinster at the RDS.
The Arms Park is once again the venue for the Blues' clash with their Belfast-based rivals as they look to build on their successful return to the city-centre venue last weekend. Gareth Baber and Justin Burnell saw their men beat Connacht 22-15 in their first game at the Arms Park since 2009 - a result that leaves them a single point behind fifth-placed Ulster with a game in hand.
The Blues have no intention of switching homes on a permanent basis but a second successive victory in front of another big crowd at their old ground would please the traditionalists and see them jump to at least fourth in the table ahead of Saturday's games.
Former All Black full back Ben Blair back was back in the thick of the action against Connacht as he picked up the Man of the Match award for his 17-point contribution having battled back from serious knee problems and, with Wales squad members Lloyd Williams and Gavin Henson both joining Blair in the starting line up and Wales veteran Martyn Williams called on to the openside flank, Baber and Burnell will be confident of over-turning September's 20-3 reverse at Ravenhill.
The Ospreys are currently the country's best-placed side as they sit second in the standings, with only last season's beaten finalists Leinster out in front. With just three losses in 14 league games so far this term, the Liberty Stadium outfit are in good shape to pick up a record-breaking fourth Celtic crown.
Neath legend Roland Phillips brings his Aironi team to Swansea without a whole host of Italian internationals and, while they have made massive strides since the former Wales back rower and Ospreys defence coach took charge, it would be a major surprise if they inflicted the Ospreys' first home league defeat of the season.
The 2005, 2007 and 2010 Celtic kings returned from Edinburgh with an impressive 15-14 win last time out and are boosted by the return to the starting line up of club captain Alun Wyn Jones. The Wales and Lions second row was a replacement in that victory at Murrayfield and will now start his first game since mid-November having fully recovered from a toe injury.
Tonight's clash with the league's bottom-placed side also marks the first game in charge for Steve Tandy. The ex-Ospreys flanker has taken over from Sean Holley as head coach and will no doubt want to begin with a bang.
If the Ospreys supporters are expecting a win this evening, it would be fair to say that the Scarlets support will travel to Ireland more in hope than expectation. Leinster have a formidable record on home soil and have scored 136 points in their last three PRO12 games at the RDS.
But while the Dubliners may be favourites to make it 13 league wins from 15 attempts, the Scarlets will fancy their chances of an upset. Prior to last week's defeat in Glasgow, Nigel Davies' troops had lost just once in their previous eight league games meaning confidence will still be high ahead of one of the biggest challenges of the Celtic calendar.
Tonight's RaboDirect PRO12 games
Blues v Ulster, 19:05, Cardiff Arms Park
Ospreys v Aironi, 19:30, Liberty Stadium
Leinster v Scarlets, 19:35, RDS