Memphis Tennessee gave the O'Brien team more success on the final day at Chester in the Boodles Diamond Ormonde Stakes.
The evens favourite pulled clear under Joseph O'Brien in the final furlong to win by four lengths from Vivacious Vivienne with newcomer Calico Cat third.
Brown Panther was a major disappointment for his breeder and co-owner Manchester United footballer Michael Owen, and trainer Tom Dascombe. He was last of the four runners after making a lot of the running in the hands of Kieren Fallon.
O'Brien junior said: "He ran a bit keen coming along the straight first time as there was a horse on my girth annoying me but after that he settled lovely.
"I took a lead and I was happy with where I was the whole way. He was just dossing up the home straight.
"He's a massive horse and a good mover. You'd like to think he's improved a lot from three to four.
"He'd certainly be a better horse on nicer ground."
