Paddington won the Prince of Wales’s Stakes to give trainer Aidan O’Brien a record 83rd victory at Royal Ascot.
The Irish 2,000 Guineas winner under Ryan Moore beat Frankie Dettori’s English Guineas victor Chaldean.
Meanwhile, Hollie Doyle became the first woman to ride a top-level Group One winner at Royal Ascot as Bradsell took the King’s Stand Stakes.
Doyle survived a stewards’ inquiry after the 14-1 winner veered left towards runner-up Highfield Princess.
Moore stole the show from Dettori, who is riding at his final Royal Ascot before retiring, with a treble sealed by Vauban after earlier winning on River Tiber.
Triple Time, trained by Kevin Ryan, sprang a 33-1 shock under Neil Callan to win the opening Queen Anne Stakes.
Inspiral was a neck back in second on a frustrating day for 52-year-old Italian Dettori.
Pregnant mare Ahorsewithnoname (7-1) provided the mother of all victories in her farewell race by winning the Ascot Stakes.
The first day’s races passed without delay after activists Animal Rising said they would not disrupt the meeting.
It is the first Royal Ascot since the death of Queen Elizabeth II last September, and King Charles III and Queen Camilla attended for the first time in their new roles.
They own several runners at the five-day fixture, although Saga could only finish fifth for Dettori in the Wolferton Stakes as 16-1 chance Royal Champion, trained by Roger Varian, gave jockey Jack Mitchell his first Royal Ascot win.
Chaldean was the 7-4 favourite in the opening day’s feature race, but it was the 11-5 shot Paddington who came out on top by three-and-three-quarter lengths.
“He’s an incredible horse, he just keeps improving and improving,” O’Brien said of Paddington.
It was a second triumph of the day for O’Brien, who earlier won the Coventry Stakes for the 10th time with River Tiber, and is now one Ascot victory ahead of Sir Michael Stoute.
Doyle, who was claiming her fourth winner at the Royal meeting, said it was “gut-wrenching” to hear the stewards’ klaxon go.
But they ruled last year’s Coventry Stakes winner Bradsell, who won by three-quarters of a length, should keep the race despite the runner-up’s rider Jason Hart saying he felt “intimidated” by the winner.
It was a sweet success for trainer Archie Watson, who had to endure Dragon Symbol losing the 2021 Commonwealth Cup after an inquiry.
Triple Time had missed the Lockinge Stakes with colic but justified his stable’s belief as he determinedly saw off the challenge of Inspital, ridden by Dettori.
“Kevin was so confident. He said it’s the best horse he’s ever trained,” said Callan.
Owner Sheikh Mohammed Obaid celebrated again later as Royal Champion sealed a double.
On her final start, Ahorsewithnoname was guided to victory by William Buick for trainer Nicky Henderson.
The eight-year-old, who is in foal to the sire Cracksman, came home in front of Calling The Wind.
Vauban led a Willie Mullins 1-2 in the concluding Copper Horse Handicap.
The evens favourite completed a Moore treble, while Dettori – aboard Absurde – finished second for the third time.
