The regular season in the Pro14 reaches a climax on Saturday with seven matches in four countries.
Defending champions Leinster have clinched the Conference B title and with it a home game in the play-off semi finals.
But Glasgow and Munster can both still win Conference A, and there is a battle for third place in Conference B between Benetton, Edinburgh and Scarlets.
Can Benetton claim a Champions Cup spot for Italy, and will any Welsh region make it into Europe's top tournament?
The final weekend - where every game is a local derby - was designed to keep interest high when there was a danger of dead rubbers dominating.
As it turns out, there's a lot more than just local bragging rights at stake.
Here's a closer look:
AT STAKE: Top spot and fourth place.
Glasgow and Munster are out to claim first place and a home draw in the Pro14 semi-finals.
Warriors face Edinburgh at home in a match that could also decide whether Edinburgh make it into the Pro14 play-offs and qualify for the Champions Cup by finishing in the top three in Conference B - more of those permutations below.
For Glasgow the equation is simple - win and they finish top of Conference A. Lose, and Munster can overtake them by beating Connacht, who are safe in third place and cannot catch Munster, who will be keen to secure home advantage in the play-offs after the disappointment of their Champions Cup semi-final defeat by Saracens.
Perhaps the most compelling match of the weekend is the Judgement Day clash at the Principality Stadium in Cardiff, where the Blues tackle Ospreys with fourth place up for grabs.
Is it strange to be worried about finishing fourth? Not if fourth secures a chance to qualify for the European Champions Cup in a play-off against the team finishing fourth in Conference A.
It boils down to that in Cardiff, with Blues trailing their rivals by a point after consecutive defeats against Munster and Connacht.
In a season where there is still a danger of no Welsh region qualifying for the premier European tournament in 2019-20, it's a big incentive.
The Blues and Ospreys might be drinking in the second chance saloon, but it promises to be quite a session...
AT STAKE: The final Pro14 championship play-off place and automatic qualification for European Champions Cup.
With the top two places sealed by Leinster and Ulster, it's all about third and fourth place in Conference B.
Benetton are currently third and strong favourites as they visit Italian rivals Zebre in their final match. It was close the last time the teams met in Stadio Sergio Lanfranchi, when Benetton won 10-8.
Zebre have won only three league matches all season - all at home against Southern Kings, Edinburgh and Cardiff Blues.
Zebre's motivation is pride, while Benetton have a Pro14 end-of-season play-off and a guaranteed place in the European Champions' Cup at stake.
Edinburgh travel to Glasgow hoping for a win and a slip-up by Benetton.
The fact the Warriors need a win to seal the Conference A crown and with it a home draw in the Pro14 semi final is an issue for the visitors. Finishing top means one game fewer in the play-offs.
It is a tough ask for Edinburgh, who could miss out on even fourth place and a play-off for Champions Cup qualification if they lose and Scarlets beat Dragons in Cardiff.
Scarlets were Pro12 Champions two years ago and Champions Cup semi-finalists last season, but have been a shadow of that side this season.
However, if Benetton and Edinburgh slip up they could still find themselves sealing third with a bonus-point win against their Welsh rivals at the Principality Stadium.
The omens are good on that front. Scarlets have won the last 10 meetings between the sides - but they need a bonus point this time in what could be the final game in charge for the coaching team of Wayne Pivac, Stephen Jones and Byron Hayward, who all join Wales next season.
Even then, Scarlets could miss out on fourth place if other results go against them. Finish fourth, however, and there will be an all-Welsh showdown with Cardiff Blues or Ospreys on 17 or 18 May, with the winners qualifying for the Champions Cup.
Scarlets have appeared in the tournament every year since the advent of regional rugby in 2003.
Quarter finals (4 May): Ulster v Connacht (QF 2); 2nd Conf B v 3rd Conf A (QF1)
Semi finals: (17 or 18 May) - Leinster v Winner QF 1; Glasgow or Munster v Ulster or Connacht
Final: (25 May) Celtic Park, Glasgow
Champions Cup play off: (17 or 18 May) - 4th Conference A v 4th Conference B (venue TBC).