We are about to acquire some useful knowledge about this Ulster side, namely if they can back up big performances away from the Kingspan and if they possess enough in the tank to cope with losing four players to injury in one game.
So much can be gleaned from this encounter that it looks to be one of those season-defining moments.
Yes, another one except that this time, should Ulster end their back-to-back matches with another win over the Scarlets then their European campaign will have admirably side-stepped extinction with two games still to play.
So, is last weekend's 24-9 bonus point relevant as Ulster regather themselves for the concluding part of this season's European double-header against the same opposition?
'Yes', in the sense that it was a win Rory Best and his players just had to deliver but also 'no' in that this is an entirely different challenge even though it is against fundamentally the same team.
Going to Parc y Scarlets needing another result against a home team with their backs to the wall in Pool Three, and one determined to make up for their serious malfunction in Belfast, means that the West Wales side are going to go all out to do themselves justice against an Ulster outfit looking more than a little patched up.
True, there is no Wiehahn Herbst, Stuart Olding, Nick Williams and Stuart McCloskey to call upon but at least Franco van der Merwe has, thankfully, recovered from his head clash with Nick Williams, and Luke Marshall - back from a medial ligament injury picked up in October - is also fit to plug the gap at inside centre, while Declan Fitzpatrick is still an adequate enough replacement for Herbst.
However, the openside flanker issue continues to rumble on and Clive Ross is parachuted in - Sean Reidy is not part of the European squad - to try and negate the excellent James Davies whose work at the breakdown could be the deciding factor tomorrow.
As a result of Williams being sidelined by his hamstring, Roger Wilson moves across to his favoured position and a lot will also ride on his workrate while Best, Robbie Diack and Dan Tuohy also need to produce massive games again.
Accuracy off the tee could also be the winning of this one and slotting two from six last weekend will simply not do for Ian Humphreys, should he again step up to take the place kicks.
With Rhys Priestland around, Neil Doak will want to ensure that Ulster can get the ball between the sticks when the opportunities arise so it will be down to Humphreys - or possibly Ruan Pienaar - to deliver the essential scores.
If the lineout improves and the scrum continues in good health, then Ulster can use these areas to launch themselves with more useful attacking plays from phase one possession to bring Tommy Bowe or Craig Gilroy into the game to give Ulster much needed momentum and belief.
And we could really get some tries if their last two encounters are anything to go by (four scores - all from Ulster - last weekend and eight in their initial PRO12 meeting back in September's 32-32 draw) but with so much riding on this game it might just come down to the more accurate side off the tee.
The benches could also tip this one and with Rory Pitman no doubt champing to get on the field, the Scarlets look that bit healthier here with Ulster now having two scrum-halves, after Michael Heaney was brought in to firefight where needed.
It will take a truly mammoth effort and though Ulster will give it everything, you feel that the Welsh just might be better equipped to get over the line first.