It is second versus fourth in Swansea with The Ospreys and Ulster two of three clubs locked on 31 points, one behind leaders Munster.
The Northern Province will have to shelve their disappointment at suffering their Champions Cup fate at another Welsh club The Scarlets last week.
It has been a very good week personally for prop Andrew Warwick, who signed a two-year contract extension, and he could come in for an immediate test against Ospreys uncompromising front row.
There is no reason to believe that the fast-moving Ospreys will be inferior to The Scarlets. They have more weapons at the ready.
It will be a case of what Ulster learned from last week and how able they are to put the recriminations into practice.
These are two foes which will already have to turn their full focus towards the PRO12 League as the European play-offs are out of reach.
"We've got ourselves into a real good position in the league," said Ospreys coach Steve Tandy.
"We're sitting second and playing Ulster who are really close to us and Scarlets who are not too far behind.
"We know it's a really important block. I think it's important we take the momentum we've created. I know we've not had the win in Europe, but we've learnt a lot."
Verdict: The Ospreys