And the Welsh region's chances of climbing the summit could be helped by the return of a brace of Lions tourists.
Wing Shane Williams and versatile back James Hook are both in line for a place in the matchday 22 as the Ospreys look to build on a hat-trick of back-to-back league victories.
Williams, who scored twice for the Lions in the historic Third-Test win over South Africa, hasn't featured for the Ospreys since the October 24 defeat at Cardiff Blues.
But coach Sean Holley is hopeful that the 2008 IRB World Player of the Year will finally return to regional colours against an Ulster side who beat reigning champions Munster last time out.
"I'm hoping Shane is really close," said Holley.
"He got up to about 90 per cent on Sunday but as a wing we need him to be as close to 100 per cent as possible."
Fellow Lions tourist Hook is also in with a good shout of featuring in Belfast after he missed the New Year's Day victory over the Blues at the Liberty Stadium.
The 24-year-old could replace Dan Biggar at fly-half, or he could slot in at inside centre now that Lee Byrne is fit enough to start at full back.
"James is very close to this week and we're very hopeful for Friday," added Holley.
"The signs are good for the weekend. We want to get him on the field this Friday and potentially we will have a look at him at some stage at 10 this week."