Waquoit, ridden by Chris McCarron, raced to his fifth straight victory Saturday in the $415,800 Brooklyn Handicap at Belmont Park.
It was the first Grade I win for the 4-year-old colt, who is owned by Joseph Federico and trained by his cousin, Guido Federico.
"He proved he was a race horse today by winning a mile-and-a-half race," Guido Federico said. "He seems to be getting better and better.
"Chris gave him a masterful ride. He allowed horses to be alongside of him but saved him for the stretch."
The trainer said Waquoit, who is unbeaten this year, may run next in the Whitney Stakes at Saratoga Aug. 8.
McCarron, who flew in from California for the race, said he had been worried about Waquoit's ability to go 1 1/2 miles.
"I was concerned about him going the distance today," he said. "He is the type of horse that only gives what he has to. I think he was tired at the end from the tremendous effort he gave."
Waquoit won by three lengths over Bordeaux Bob, while 27-1 outsider Full Courage finished third, 10 lengths behind the runner-up and 7 1/2 lengths in front of Cutlass Reality.
Carrying top weight of 123 pounds, Waquoit conceded from 9 to 17 pounds to his eight rivals.
The 4-year-old gray son of Relaunch-Grey Parlo was on or close to the lead throughout, finishing the 1 1/2 miles in 2:28 2/5 in 95-degree temperature.
It was the third straight stakes victory for the New England-based colt. Waquoit previously won the Massachusetts Handicap at Suffolk Downs and the Michigan Mile at Detroit.
Sent off as the 3-2 favorite, the winner paid $3.20, $2.80 and $2.40. Bordeaux Bob returned $3.60 and $2.80, while Full Courage paid $5.20.
The win was worth $249,480, raising Waquoit's career earnings to $767,524. He has 16 wins in 21 starts.
Coup De Fusil, ridden by Angel Cordero, won the 50th running of the Delaware Handicap at Delaware Park and set a track record of 1:59 2/5, beating the previous record of 2:00 for the 1-mile race set by Heavenly Ade in 1980.
Cordero also won the race aboard Politely in 1968, Krislin in 1974 and Relaxing in 1981.
The race, valued at $114,600, returned $68,760 to Tartan Stable, which owns the 5-year-old mare trained by Jan Nerud.
Coup De Fusil paid $7.20, $4.80 and $3.40. Steal A Kiss, owned by Dan Galbreath, finished second and paid $9.40 and $3.80. Catatonic, the 2-1 favorite, finished third and paid $2.60.
The victory by Cordero was his 5,998th. Only three jockeys have won 6,000 or more races: Johnny Longden, Bill Shoemaker and Laffit Pincay.
At Oceanport, N.J., Without Feathers beat Single Blade by 6 1/2 lengths in the $160,400 Grade I Monmouth Oaks for 3-year-old fillies at Monmouth Park.
Ridden by Chris Antley, Without Feathers covered the 1 1/8 miles in 1:48 and paid $5.60, $3.20 and $2.40. The Wayne Lukas-trained horse earned $66,200 for owner Dennis Donahue.
Single Blade finished second and paid $3.30 and $2.40, with Grecian Flight returning $2.40 to show.
At Arlington Heights, Ill., Complice II, a 6-year-old French-bred horse ridden by Fernando Toro, swept past four rivals in the stretch to win the 34th running of the $84,900 Laurence Armour Handicap at Arlington Park.
Autumn Glitter, the only filly in the field of 10 turf runners, finished second, half a length behind the winner.
Explosive Darling, the 3-2 favorite in the 1 1/2-mile race, was 1 1/2 lengths back in third after holding a half-length lead with a furlong to go.
Complice II, making his fourth start in the United States after racing in France, carried Toro home in 2:30 2/5 and paid $10, $4.80 and $2.40. Autumn Glitter returned $3.80 and $2.20, while Explosive Darling paid $2.20.