Decorated Knight was last as the field turned into the straight in the QIPCO Irish Champion Stakes (G1) Sept. 9, then he circled wide and ran by them all to win by a half-length.
Race-favorite Churchill had nowhere to go on the rail and faded to finish seventh.
Decorated Knight, under Andrea Atzeni, trailed through most of the 10 furlongs before he made the winning move. Pacesetter Eminent held his ground well into the lane and finished third, edged late for second by Poet's Word.
Decorated Knight finished in 2:08.36 over ground rated good to yielding.
"Andrea said he knew he was going to win turning in. I couldn't believe it," trainer Roger Charlton said. "He's tough, consistent, and very sound. He produced an amazing turn of foot and ran right to the line."
Dual Guineas winner Churchill, trainer Aidan O'Brien's top hope for the race, was always close, but jockey Ryan Moore had nowhere to go in the final 100 yards and the gaps in front of him closed before he could take advantage. as Moonlight Magic ranged up on his outside. Churchill suffered his third straight defeat after seven consecutive wins.
The Champion Stakes was one of three Breeders' Cup Challenge races on the card at Leopardstown, and Decorated Knight earned a fees-paid spot in the starting gate for the Longines Breeders' Cup Turf (G1T). The 5-year-old son of Galileo, owned by his breeders, Saleh Al Homaizi and Imad Al Sagar, already has given Charlton no shortage of options this season.
He won the Betway Winter Derby Trial Stakes over the Lingfield all-weather course in February and was a prime candidate for the All-Weather Championship finals on Good Friday. Instead he went to Dubai, where he won the Jebel Hatta Sponsored by Emirates Airline (G1) March 4 at Meydan Racecourse.
Following a sixth-place run in the March 25 Dubai Turf Sponsored by DP World (G1), Decorated Knight returned home and won the Tattersalls Gold Cup (G1) at the Curragh. He then finished second to Highland Reel in the Prince of Wales's Stakes (G1) at Royal Ascot before back-to-back off the board efforts behind Ulysses in the July 8 Coral-Eclipse (G1) and Aug. 23 Juddmonte International Stakes (G1).
"He's been a bit unlucky in his last couple of races," Charlton said. "He hated the ground at York, got bashed about at Sandown in the Eclipse, and ran a great race at Royal Ascot. He's been on the go since March, and he's improved and improved. To keep going all season is a tribute to the horse."
Hydrangea, one of four in the race trained by O'Brien, tracked another of that quartet, Roly Poly, into the stretch run in the one-mile Matron. Winter took over the point some 100 meters out and ran on well, but the multiple group 1 winner could not deny Hydrangea, who prevailed by a head under Wayne Lordan.
Persuasive finished third with a late move on the outside and Roly Poly faded to finish sixth.
Hydrangea, a 3-year-old Galileo filly out of the Pivotal mare Beauty Is Truth, previously suffered four straight group 1 losses at the hands of Winter, including a fourth-place finish to her Ballydoyle mate in the Aug. 3 Qatar Nassau Stakes (G1) at Goodwood. Hydrangea's last win prior to Saturday came when she bested the future dual Guineas winner in the Ballylinch Stud One-Thousand Guineas Trial Stakes (G3) in April, which was also contested over the Leopardstown course.
"She was the only one of the four fillies that had not won a group 1," O'Brien said of Hydrangea. "We felt that Winter was going to improve a bit from the run. She was carrying a little bit of a tummy, but needed to run.
"I'm delighted for the filly and I'm delighted for Wayne. She is Winter's work partner all year, and maybe she turned around and said 'Hydrangea, you can have this one today.'"
The Matron is a Breeders' Cup Challenge race that provides a fees-paid entry for the Breeders' Cup Filly & Mare Turf (G1T) at Del Mar. O'Brien, however, indicated both of his top two are headed for Chantilly, with Winter still a possibility for the Qatar Prix de l'Arc de Triomphe (G1) Oct. 1.
"Nothing surprises me anymore," the trainer said of the Matron upset. "The winner will stay further. She could go for the Prix de l'Opera (G1). Winter is in the Arc, and the Opera is another option."
The third Breeders' Cup berth up for grabs went to Nelson, another O'Brien charge, who made the most of the going in the Willis Towers Watson Champions Juvenile (G3) and won by three lengths over stablemate Kew Gardens. Delano Roosevelt finished third for an O'Brien sweep of the top three placings.
Nelson, a Frankel colt out of the Dalakhani mare Moonstone, won his second straight race to earn spot in the Breeders' Cup Juvenile Turf (G1T). Donnacha O'Brien had the winning ride.