Portrush - Home favourite Rory McIlroy and Tiger Woods both endured dreadful starts to the Open Championship on Thursday, while American JB Holmes claimed the lead as the championship returned to Royal Portrush for the first time since 1951.
Organisers the R&A are anticipating the second-biggest ever Open attendance, with 237 750 people expected to come through the gates this week in Northern Ireland, but spectators were left stunned by McIlroy's immediate collapse.
He briefly battled back after a bogey at the par-three third hole, but missed a tiny putt to double-bogey the 16th, tripled-bogeyed the last and eventually carded a disastrous eight-over 79.
"I guess when you play your first and last holes in a combined seven over par you are starting on the back foot," said McIlroy.
The four-time major champion, who fired a course-record 61 at Portrush at the age of just 16 in 2005, was given a huge reception on the first tee as the crowds huddled around the opening hole for a sight of the local hero.
But he quadrupled-bogeyed the first after hitting his tee shot out of bounds.
Woods saw his bid for a 16th major title all but come to a premature end as he stuttered to a miserable seven-over 78, including six bogeys and a double bogey at the par-three sixth.
The Masters champion's sole birdie of the day came at the par-four 15th, which he celebrated with an ironic raise of his arms, but he fittingly finished his round with one last bogey.
Woods, who returned from spinal fusion surgery in December 2017, and McIlroy now face daunting tasks to try and make the cut.
"Wasn't hitting it solid. Everything was off the heel. Just trying to scrape it around. Best I could do was seven-over," said Woods, who admitted he was feeling "sore".
McIlroy is already 13 strokes adrift of leader Holmes -- with Woods one better off -- after the 37-year-old birdied the 18th to post an excellent five-under 66 and move one shot clear of previous leader Shane Lowry.
Holmes' previous best major finish was third at the 2016 Open and he has missed eight cuts in his last 13 events, and withdrew from one of the others.
"I've been practising the last couple of weeks. I've been playing great. So actually felt great coming in," said the 55th-ranked Holmes.
Ireland's Lowry held the lead for much of the day before being toppled by Holmes, having to settle for second place heading into Friday.
The world number 33, who made five birdies in his 67, admitted he struggled to keep his nerves in check on the first tee, with the crowds lending strong support to all six players from the Republic of Ireland and Northern Ireland.
"It's the British Open, it's in Ireland. I feel like I'm hitting it well. Of course I feel uneasy," he said.
There is a group of 13 players in the clubhouse just two strokes off the lead on three-under, including world number one Brooks Koepka and Spaniard Jon Rahm.
American Koepka made his only bogey of the day on the penultimate green, but felt he could have done much better.
"Didn't really make any putts. Didn't take advantage of anything to really go low," said Koepka, who has finished in the top two of all three majors this year and is looking to add the Claret Jug to his two US Opens and two PGA Championship titles.
Rahm, who won his second Irish Open title at Lahinch two weeks ago, held the lead on his own on various occasions, but dropped back with bogeys at the 15th and 18th holes.
English pair Tommy Fleetwood and Lee Westwood are also among those on three-under, with the latter still looking for his maiden major title in his 25th consecutive British Open appearance.
Ryan Fox of New Zealand had a record-breaking day with the lowest back nine in Open history as he came home in 29 to get to join the pack of players who signed for 68s.
Reigning champion Francesco Molinari saw his hopes of becoming the first man to defend the title since Padraig Harrington in 2008 take a blow, only managing a three-over 74.
Argentina's Emiliano Grillo got the crowds excited with the first hole-in-one at the championship since 2016 on the par-three 13th.
Scores from the first round of the British Open at Royal Portrush on Thursday (par 71):
66 - JB Holmes (USA)
67 - Shane Lowry (IRL)
68 - Sergio Garcia (ESP), Jon Rahm (ESP), Ryan Fox (NZL), Dylan Frittelli (RSA), Alexander Norén (SWE), Kiradech Aphibarnrat (THA), Brooks Koepka (USA), Tony Finau (USA), Webb Simpson (USA), Tommy Fleetwood (ENG), Lee Westwood (ENG), Tyrrell Hatton (ENG), Robert MacIntyre (SCO)
69 - Romain Langasque (FRA), Park Sang-Hyun (KOR), Justin Rose (ENG), Ashton Turner (ENG)
70 - Cameron Smith (AUS), Jason Day (AUS), Bernd Wiesberger (AUT), Lucas Bjerregaard (DEN), Shubhankar Sharma (IND), Yuki Yuki Inamori (JPN), Kim Si-Woo (KOR), Erik Van Rooyen (RSA), Louis Oosthuizen (RSA), Branden Grace (RSA), Rory Sabbatini (SVK), Henrik Stenson (SWE), Charley Hoffman (USA), Patrick Cantlay (USA), Kevin Kisner (USA), Jordan Spieth (USA), Andrew Putnam (USA), Matt Kuchar (USA), Rickie Fowler (USA), Eddie Pepperell (ENG), Callum Shinkwin (ENG), Russell Knox (SCO)
71 - James Sugrue (IRL), Hideki Matsuyama (JPN), Mikumu Horikawa (JPN), Im Sung-Jae (KOR), Zander Lombard (RSA), Ernie Els (RSA), Justin Harding (RSA), Justin Thomas (USA), Patrick Reed (USA), Doc Redman (USA), Matthew Fitzpatrick (ENG), Darren Clarke (NIR)
72 - Thomas Pieters (BEL), Corey Conners (CAN), Thorbjorn Olesen (DEN), Mikko Korhonen (FIN), Nino Bertasio (ITA), Yosuke Asaji (JPN), Hwang Inn-Choon (KOR), Abraham Ancer (MEX), Brandon Stone (RSA), Gunn Charoenkul (THA), Aaron Wise (USA), Lucas Glover (USA), Bubba Watson (USA), Dustin Johnson (USA), Brian Harman (USA), Paul Casey (ENG), Curtis Knipes (ENG), Connor Syme (SCO)
73 - Emiliano Grillo (ARG), Rafael Cabrera (ESP), Adrián Otaegui (ESP), Alexander Levy (FRA), Benjamin Hébert (FRA), Andrea Pavan (ITA), Takumi Kanaya (JPN), An Byeong-Hun (KOR), Joost Luiten (NED), Shaun Norris (RSA), Prom Meesawat (THA), Brandon Wu (USA), Keegan Bradley (USA), Luke List (USA), Chez Reavie (USA), Jim Furyk (USA), Patton Kizzire (USA), Chris Wood (ENG), Oliver Wilson (ENG), Andrew Johnston (ENG), Matt Wallace (ENG), Graeme McDowell (NIR)
74 - Adam Hadwin (CAN), Li Haotong (CHN), Francesco Molinari (ITA), Kang Sung-Hoon (KOR), Mun Doyeob (KOR), Christiaan Bezuidenhout (RSA), Jazz Janewattananond (THA), David Lipsky (USA), Bryson DeChambeau (USA), Kurt Kitayama (USA), Xander Schauffele (USA), Ryan Palmer (USA), Zach Johnson (USA), Brandt Snedeker (USA), Stewart Cink (USA), Jason Kokrak (USA), Gary Woodland (USA), Jimmy Walker (USA), Danny Willett (ENG)
75 - Austin Connelly (CAN), Adrià Arnaus (ESP), Padraig Harrington (IRL), Yoshinori Yoshinori Fujimoto (JPN), Isidro Benítez (MEX), Chan Kim (USA), Keith Mitchell (USA), Kyle Stanley (USA), Nate Lashley (USA), Paul Waring (ENG), Ian Poulter (ENG), Tom Lewis (ENG), Jack Senior (ENG), Sam Locke (SCO), Paul Lawrie (SCO)
76 - Jake McLeod (AUS), Joaquin Niemann (CHI), Jorge Campillo (ESP), Matthias Schmid (GER), Yuta Ikeda (JPN), Jang Dong-Kyu (KOR), Joel Dahmen (USA), Phil Mickelson (USA), Billy Horschel (USA), Andy Sullivan (ENG), Robert Rock (ENG), Andrew Wilson (ENG)
77 - Michaël Lorenzo-Vera (FRA), Alexander Björk (SWE), Kevin Streelman (USA), Cheng Tsung Pan (TPE)
78 - Adam Scott (AUS), Marc Leishman (AUS), Richard Sterne (RSA), Tiger Woods (USA), Tom Lehman (USA), Matthew Baldwin (ENG)
79 - Garrick Porteous (ENG), Rory McIlroy (NIR)
82 - Miguel Ángel Jiménez (ESP)
83 - Dimitrios Papadatos (AUS), Shugo Shugo Imahira (JPN), Thomas Thurloway (ENG)
91 - David Duval (USA)