Former champions Louis Oosthuizen and Jordan Spieth were the early front-runners on Day 1 of The Open at Royal St George's on Thursday.
South African Oosthuizen, who won the tournament in 2010, sank six birdies on his way to an immaculate six under par 64, while 2017 winner Spieth finished one shot behind.
Oosthuizen, 38, played his irons beautifully to pick up three birdies around the turn and added three more on the closing holes to finish with a career-low score in a major. It was also the lowest score by any player in major during the 2020-21 season.
"Probably in my mind it was the perfect round I could have played," he said. "I didn't make many mistakes. When I had good opportunities for birdie, I made the putts. So, yeah, just a very good solid round."
Spieth made four consecutive birdies from the fifth and sank a 12-foot putt on the 16th green to confirm the 27-year-old's return to form after finishing 2020 world rankings down in 82. The American is currently back up to No 23.
Brian Harman matched his compatriot Spieth with a 65 to share second place, one clear of Canadian Mackenzie Hughes, South African Dylan Frittelli and veteran American Stewart Cink, who won the tournament in 2009.
England's Justin Rose, Danny Willett, Andy Sullivan and Jack Senior carded 67s along with South African Justin Harding, American Scottie Scheffler and South Korea's An Byeong-Hun.
Shane Lowry was left to rue a stroke of misfortune after finally getting the defence of his Open title under way at Royal St George’s.
More than 700 days after he lifted the Claret Jug at Royal Portrush, Lowry recovered from a shaky start to get back to level par before dropping a shot on the 18th.
The resulting 71 left him seven shots behind playing partner Oosthuizen after he set the early clubhouse target. Also playing alongside the pair was US Open champion Jon Rahm, who carded a 71 that included a double bogey at the ninth.
“I’d say I played pretty average,” said Lowry, who was prevented from defending his title last year when the Open was cancelled due to the coronavirus pandemic.
“I didn’t play my best golf but then again, you’re playing with Louis who’s shooting six under and playing great. It kind of makes you feel a little bit different.
“I’m disappointed to bogey the last. I think if I would have parred the last and shot level par I would have been quite happy with myself going home this afternoon, but I didn’t.
“I got an unfortunate bounce and went into the bunker and made bogey. But I battled hard. I was quite proud of myself.”
But the 34-year-old was still able to enjoy the atmosphere generated by the 32,000 fans allowed on site. “It was great. It was a very special day for me,” Lowry said. “The announcement on the first tee, I’ve been waiting over a year for that, so it’s quite nice.
“It was quite unsettling at the start. I got off to a pretty nervy start.
Big-hitting American Bryson DeChambeau - the 2020 US Open winner - battled to a round of 71, while world No 1 Dustin Johnson started with a solid 68.
Four-times major champion Rory McIlroy, British Open winner in 2014, was among the late starters along with PGA Championship winner Phil Mickelson.