Cardiff Blues head coach Danny Wilson says their 35-17 Judgement Day victory over the Ospreys was the most pleasing of his tenure.
The Blues defeated the Ospreys in the Pro12 for the first time since December 2010 thanks to dominant performance.
Five tries saw them build up a 35-3 lead before a couple of late tries flattered the Ospreys.
"It was outstanding. Derbies are won on physicality and we've come second to them a number of times," he said.
He continued: "Today we definitely won that battle. We were physical, put our imprint on the game and scored some fantastic tries.
"For 50 minutes we were in complete control. It was probably the most pleasing under my reign with beating them in the stadium.
"The Ospreys have an impeccable record in derbies and to beat them is a huge achievement."
It was a fourth successive defeat for the Ospreys in all competitions, with the region now clinging on to hopes of a top four play-off finish.
'Not enough fight'
Ospreys head coach Steve Tandy criticised their attitude and admitted his side had been bullied in certain areas.
"We knew it was going to be a tough game with the way the Blues have been playing," said Tandy.
"The Blues dominated us around the breakdown. Their attitude and commitment in that area was far greater than ours and we were bullied at the breakdown.
"We didn't show enough fight and desire and one or two of them were feeling sorry for themselves which is not something you see too often in an Ospreys changing room."
Missing captain Jones
Wales captain Alun Wyn Jones has been missing in the Ospreys' losing run through a shoulder injury picked up in Wales' Six Nations finale against France.
Tandy insisted he would not be rushed back for the final two games against Ulster and the Scarlets.
"He is in around the group, he has done a bit of lifting," said Tandy.
"His rehab is sticking, Al is going to be at the centre of what we do, it won't be a reaction of 'we need him back'.
"We won't put him at risk, we will speak with the medical team, see where he is at for the last two games of the season."