A first-half try from hooker Ifan Phillips gave Ospreys a 7-3 half-time advantage.

Cardiff Blues had forwards Seb Davies, Dmitri Arhip and Scott Andrew yellow-carded in the second-half as they played most of the period with 14 men.

The hosts could only manage a Jason Tovey penalty in response at their temporary home venue.

Ospreys flanker Dan Lydiate had been yellow-carded in the first-half for a high challenge on Cardiff Blues fly-half Jason Tovey.

Referee Ben Whitehouse considered a red card for Lydiate but 10 minutes in the sin-bin was awarded.

Watching Wales coach Wayne Pivac would have been content with a powerful ball-carrying performance by wing George North ahead of next month's Six Nations.

Stadium switch

Cardiff Blues returned to Cardiff City Stadium for the first time in nine years for the first of two home matches.

Blues had played at the ground for three years between 2009 and 2012 before returning to the Arms Park.

They vacated their home in 2020 because it became part of the Principality Stadium field hospital complex.

While the stadium was out of action, Cardiff Blues have also used Rodney Parade in Newport as a temporary home.

John Mulvihill made eight changes which included Wales forwards Rhys Carre and Shane Lewis-Hughes starting. Wales flanker James Botham was a late withdrawal with Alun Lawrence starting.

Centre Rey Lee-Lo returned, while Tomos Williams replaced fellow Wales scrum-half Lloyd Williams.

Ospreys also made a change at scrum-half, with Rhys Webb starting in place of Reuben Morgan-Williams, while centre Kieran Williams replaced Tiaan Thomas-Wheeler in midfield.

Toby Booth made four changes to the pack, including a new front row of Rhodri Jones, Ifan Phillips and Ma'afu Fia and the inclusion of number eight Sam Cross.

There was an enterprising opening Ospreys period involving Justin Tipuric and North, while half-backs Webb and Stephen Myler kept the visitors going forward with clever probing kicks.

There was the now traditional kick tennis between the two sides, while Ospreys centre Scott Williams was forced off with a shoulder injury which could mean a long lay-off.

A clean counter-attack from Hallam Amos and support play from Tomos Williams set up the platform to Tovey to open the scoring after Webb was penalised for a deliberate knock-on.

Ospreys responded with the game's opening try with a powerful driving lineout allowing hooker Ifan Phillips to cross and Myler converted.

A superb break from North from his own 22 was followed by Lydiate thrusting his arm into Tovey when in possession.

After numerous television replays, referee Whitehouse deemed it a yellow card offence for Lydiate with the officials judging there was no clear indication he had made contact with Tovey's neck or head.

Myler missed an early second-half penalty chance to extend the lead after Josh Turnbull and Arhip collided into each other.

Cardiff Blues lock Davies was yellow-carded for driving into an Ospreys lineout just as Lydiate returned to the field.

North again powered through the Cardiff Blues defence and although a try was spurned, Myler slotted over a penalty.

The hosts had just been restored to 15 men before Arhip was yellow carded for collapsing an Ospreys driving maul with a penalty try awarded.

Cardiff Blues wing Josh Adams denied Ospreys captain Justin Tipuric a try with a touchline tackle before prop Andrews was yellow-carded after being dominated by the visitors scrum.

There was a nasty incident in the final minute when Cardiff Blues centre Garyn Smith was stretchered off injured.

Ospreys head coach Toby Booth said: "It was good reward for the effort we put in during the game and I am delighted with that.

"You build a lot of your performances on set-piece and we were dominant in that area tonight which is fantastic.

"It makes the game a lot easier to play on the front foot than the back foot and you make yourselves harder to beat.

"The exciting thing for me is this group were disappointed afterwards they were not further ahead on the scoreboard."

Cardiff Blues head coach John Mulvihill said: "In these games we need to play well enough to deserve to win and we did not play well enough tonight and that's what we got.

"We can't give away 19 penalties and three yellow cards and come out the right side. I was really disappointed with our discipline.

"We need to clean that up. The intensity was not here for us tonight for a lot of periods and the Ospreys did have that.

"The venue was fantastic. It did not get the spectacle of rugby but it's an awesome venue to play in."

Cardiff Blues: Amos; Adams, Lee-Lo, Smith, Summerhill; Tovey, T Williams; Carré, Dacey, Arhip, S Davies, Thornton, Lewis-Hughes, Lawrence, Turnbull.

Replacements: Belcher, Domachowski, Andrews, Ratti, B Murphy, L Williams, Scully, Halaholo.

Ospreys: Evans; North, S Williams, K Williams, Morgan; Myler, Webb; Jones, Phillips, Fia, Beard, Davies, Lydiate, Tipuric (capt), Cross.

Replacements: Otten, Smith, Botha, Ashley, Griffiths, Morgan-Williams, Wheeler, Protheroe.

Referee: Ben Whitehouse (WRU)

Assistant Referees: Craig Evans and Dan Jones (both WRU)

TMO: Rhys Thomas (WRU)