Defending champions Glasgow Warriors will take their seven-match winning streak on the road to Wales to face fourth-placed Scarlets - a side they have faced three time already this season in Europe and the league.
Warriors took over Scarlets' third-place spot in the table by beating Zebre last time out, and victory here could, other results pending, propel them towards a home play-off.
Scarlets, who have been in the top four since round two, need a victory to maintain their own challenge for the knockout phase.
From a personal point of view, DTH van der Merwe will have Matt Healy in his sights in the try-scoring charts - the Canadian star has seven tries to Healy's nine at the moment.
'Super Saturday' also includes a pivotal game at the Sportsground in Galway and an all-Irish clash between Connacht and Munster.
Connacht have to put the disappointment of their European Challenge Cup exit behind them to concentrate on their quest for a first ever Guinness PRO12 title but need to overcome three-time champions Munster first.
They have never before achieved a season's double over their southern neighbours but should they achieve that they could all but end Munster's hopes of playing the PRO12 play-offs for the third year in a row.
Winger Healy - who was in inspired form last time out in Europe - will look to extend his lead atop the try scoring standings while for Munster Johnny Holland has a perfect 100 per cent record from the kicking tee.
Round 20 starts on Friday night and table-topping Leinster host seventh-placed Edinburgh Rugby. Victory is vital for both teams' prospects: Leinster to maintain their push for a home play-off; Edinburgh to try and ensure there are two Scottish qualifiers in the 2016/17 Champions Cup; but there can be only one winner.
Leinster's Isa Nacewa on seven tries and Edinburgh's Damien Hoyland on eight tries will both be hoping to catch Healy as well.
Jason Tovey is leading the way in the Rhino Golden Boot standings, the former Dragon has an 82.05% success rate to top the charts and Leinster will need to beware that.
For Leinster, two tries for Jamie Heaslip will take him to 25 for his PRO12 career.
That same milestone is available to Ospreys' scrum-half Rhys Webb but the Welsh region will face tough competition from a Benetton Treviso side still trying to make up ground on Zebre who currently hold the designated Italian place in next season's European Champions Cup.
Sam Davies is also challenging for the top points scorer with 152 (currently second), while Jayden Hayward of Treviso is third on 141.
Zebre need as many points they can gain when they welcome Ulster to stave off the challenge from Treviso for a place in Europe's top tier next season.
Should the result of the earlier game go Ulster's way, victory over Zebre could see Les Kiss' side return to the top four while fly-half Paddy Jackson needs 28 for 500 in his PRO12 career.
The round wraps up on Sunday with European Challenge Cup semi-finalists Newport Gwent Dragons heading to fellow Welsh region Cardiff Blues at BT Sport Cardiff Arms Park.
Both teams are hoping to represent Wales in the Champions Cup next season, but whilst Dragons could progress through the Challenge Cup, Blues must look towards the Guinness PRO12 top six for their route as top points scorer Rhys Patchell leads the way.
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