Moyenne Corniche mounted a late surge to win the Ebor Handicap at York for trainer Brian Ellison.
The 25-1 chance, ridden by Dale Swift, burst through inside the final furlong to win the hotly contested feature race on the Knavesmire.
Tactician (9-1) was a length adrift in second with another 25-1 shot Investissement finishing third ahead of Richard Hughes' mount Modun (7-1).
"He did it well and travelled so nicely," said Swift.
"I didn't want to get there too soon and he stuck his neck out really well.
"We didn't go a great gallop, but he wasn't too keen and we got the gaps when we needed them. You just have to take your time with him and he needs that little bit of dig in the ground."
Tactician tried to make all for handler Michael Bell and jockey Joseph O'Brien, but the challengers were queuing up three furlongs out as the field came down the centre of the track on the final day of the extended four-day Ebor Festival.
Mount Athos threatened briefly with Investissement and Modun challenging strongly, but 3lb claimer Swift timed it to perfection on Moyenne Corniche to race home.
Local trainer Ellison, who also saddled the well-fancied Saptapadi, added: "The plan was to hit the front late, I knew he would love the ground and I said to Dale he wouldn't be out of the first four.
"I think the other horse (Saptapadi) might have won if we had dropped him out, he was too keen."