Gun Runner produced a stunning front-running performance to run out a convincing winner of the Breeders' Cup Classic at Del Mar.
Defeated in all three previous attempts over a mile and a quarter, as well as in both prior meetings with Arrogate, Florent Geroux took little time to get Gun Runner to the front of the field, as fellow market leader Arrogate jinked left at the start and was floundering from then on.
Collected made a big effort to get alongside Gun Runner on the turn for home, but Steve Asmussen's charge would not be denied and charged clear in the home straight.
Bob Baffert had the second and third in Collected and West Coast, but his Arrogate was never in contention on the final start of his career, while Aidan O'Brien's Churchill was prominent early but was well beaten long before the home straight.
Geroux said: "It wasn't really the plan (to go straight to the front), it was how the race unfolded. He can go on the lead and can stalk if the pace is hot. He's just a beast."
An ecstatic Asmussen, who won with the mighty Curlin in 2007, said: "I can't tell you how proud I am of him. This is in the moment, it couldn't be better in the moment."
Last year's winner Arrogate ended his glittering career as the highest-earning horse in history.
Baffert said: "When he goes around these turns, he loses momentum, but I can't totally blame the track, he's not where he was.
"He's so much better than that and it's so disappointing to see him go out like that. He's one of the greatest horses I've trained."
His ride Mike Smith said: "I'm lost for words, to be honest. He didn't run his race at all, but it is what it is - I know how good he is."
O'Brien, who was in the winner's enclosure with Mendelssohn on Friday night, said: "It was all new to Churchill (seventh). War Decree (ninth) will now go back to a mile and a quarter on grass.
"It's been a very enjoyable week for us overall, with a lot of our horses running well."