Brown Panther could only manage second in the Group 2 Prix Maurice de Nieuil at Longchamp as Terrubi proved too strong in the closing stages.
Held up off a strong gallop by Richard Kingscote, Brown Panther was going well on the outside towards the rear throughout and made his move in the home straight.
However, Christophe Soumillon was aware of his every move on Terrubi and the grey Pascal Bary-trained colt kicked clear of Tom Dascombe's charge inside the final furlong.
Brown Panther tried hard to get on terms with this rival, but the improving four-year-old had things under control and ran out a fairly comfortable winner.
Michael Owen's Brown Panther had to hold on for second in the end from the fast-finishing Going Somewhere.
Kingscote said: "He ran well, he relaxed really well but the winner picked up at the two-furlong pole and there was nothing we could do.
"When I first came upsides the winner I thought I was still going reasonably well, but he just had another gear."
Dascombe said: "He has run his race, he settled well and travelled.
"I think we were virtually upsides the winner turning in, and he just quickened up better than us.
"We've got no excuses, it's a shame we got beat but he will go to Goodwood now."