The favourite Epatante gave owner JP McManus a birthday to remember with victory in the Champion Hurdle on the opening day of the Cheltenham Festival.
Barry Geraghty had the 2-1 shot, trained by Nicky Henderson, well-placed throughout in Tuesday's showpiece race.
After jumping the last strongly, the six-year-old mare ran on up the hill to beat Sharjah into second.
There was another Grade One victory for jockey Rachael Blackmore aboard Honeysuckle in the Mares' Hurdle.
Great eight for Henderson
Henderson extended his exceptional Champion Hurdle record to eight victories, while it was a record-equalling fourth win for Geraghty.
And it was a ninth success in the race for McManus, who was celebrating his 69th birthday.
Just as the Festival has gone ahead after doubts caused by the coronavirus outbreak, so the big-race winner recovered from a scare.
The mare had "coughed a few times," her trainer had revealed 12 days before the race.
"She coughed for a couple of days and I felt I had to say something," said Henderson.
"She must have read the newspapers and as soon as she read the papers, she recovered."
Geraghty guided his mount to a three-length victory from Sharjah, with Darver Star third.
"JP is sourcing this talent and he supports the game at every level," said the jockey.
"The birthday cheer he got today reflects what people think of him because he is a top-class man."
Last year, Epatante disappointed when she finished well down the field in the Mares Novices' Hurdle, but two wins at Newbury and in the Christmas Hurdle at Kempton left her at the top of the betting market coming into the Festival.
Henderson was celebrating a 20-1 double after Shishkin edged out Abacadabras to win the Supreme Novices' Hurdle.
Victory put him one ahead of Willie Mullins on 66 career Festival victories as the meeting's all-time leading trainer.
Sweet victory for Blackmore
Blackmore started the week as third favourite to be the meeting's leading jockey and demonstrated all her ability when landing the Mares' Hurdle.
She slipped through on the inside on 9-4 shot Honeysuckle around the final bend and took the initiative from 4-6 favourite Benie Des Dieux, ridden by Paul Townend, following a pulsating duel.
"That was just the way it worked out," she said.
"It's every jockey's dream to be in the position I'm in and Cheltenham is what it's all about."
It was a second winner on the opening day for trainer Henry de Bromhead, who scored with 16-1 shot Put The Kettle On in the Arkle Chase.
Benie Des Dieux had fallen while leading at the final flight under Ruby Walsh last year, and trainer Willie Mullins believes there may have been a "miscommunication" this time around.
"Maybe Robbie [Power, riding stablemate Stormy Ireland] thought that one of our horses was behind him, rather than Honeysuckle," explained Mullins.
"It looked like he just gave the winner a huge gap while Paul was going round the outside. Things happen. We won't want to watch that again."
The Conditional, under Brendan Powell for David Bridgwater, won the Ultima Chase while another Gloucestershire trainer, Kim Bailey, took the Novices' Handicap Chase with Imperial Aura, ridden by David Bass.
Leading amateur jockey Jamie Codd claimed a 10th Cheltenham Festival success with victory aboard Ravenhill, trained by Gordon Elliott, in the National Hunt Chase.
Crowd down after meeting uncertainty
The opening-day crowd of 60,664 was significantly down on recent years after doubts over whether the meeting would go ahead.
This compares to an opening attendance of 67,934 in 2019, and was the lowest for the Tuesday for six years.
"We are very happy with the crowd considering the uncertainty of the last fortnight," said Cheltenham chief Ian Renton.
Organisers had laid on 24 hand sanitiser banks, with the caption "Don't Pass It On", in a hygiene drive aimed at combating any spread of coronavirus.
There were 14 extra toilet units installed, and posters with government advice on hand-washing techniques.
'Epatante is clearly thriving' - analysis
Cornelius Lysaght, BBC horse racing correspondent
Epatante dominated the race like the very good horse she clearly is, becoming in the process a rare Champion Hurdle success by a female horse, and defying those who feared that the examining final hill might be too much for her.
She's only six, is clearly thriving and will set a decent standard for the future even if some will point to the fact that it was probably not a vintage staging.
The unbeaten Irish mare Honeysuckle might have taken her on, but went for the mares-only Hurdle and came away with a memorable success ridden by Rachael Blackmore.