Leaders Exeter Chiefs suffered a third Premiership defeat of the season at Gloucester, while Wasps moved into the top four.
Centre Stuart McCloskey celebrated a century of matches for Ulster by dotting down for the only try against the Ospreys.
Following a head injury against Scotland, Johnny Sexton is fit again and in the running to play for Ireland in Italy.
Wales were dealt a blow on Friday as Leigh Halfpenny's expected comeback for the Scarlets did not come to fruition.
Sio Tomkinson's red card made a Highlanders comeback look unlikely, but Aaron Smith had other ideas and punished the Chiefs.
Eddie Jones sought to dismiss Wales' strong record in Cardiff ahead of England's Six Nations visit, but Neil Jenkins is not worried.
Owen Franks is looking forward to a new adventure in the Premiership after agreeing to join Northampton Saints.
Ellis Genge was removed from training on Thursday, but Steve Borthwick does not think there will be any 'major consequences' for the prop.
Having lost Ryan Wilson for the rest of the Six Nations earlier this week, Scotland may also have to cope without Huw Jones.
There were concerns that Iain Henderson would not feature in the Six Nations, but the lock looks set to play a part for Ireland.
Despite missing the playoffs for the first time in six seasons last year, Brumbies have handed Dan McKellar an extension.
Leigh Halfpenny will get the chance to prove his fitness ahead of Wales' clash with England by featuring for the Scarlets this weekend.
Matthew Rees is eager to end his long career on a high note by securing a European Rugby Champions Cup spot for Cardiff Blues.
Gregor Townsend is optimistic there will be good news on Stuart Hogg's shoulder injury when he visits a specialist.
A back injury has ended Scott Williams' hopes of participating in Wales' Six Nations campaign.
Eddie Jones' England have made a flying start to the Six Nations and next up is a trip to Cardiff to face Wales.