After the 149th British Open Championship got underway under blue skies at Royal St. George's in Kent on Thursday, golfer Louis Oosthuizen leads the charts after the first round as a six under par 66 from the South African put him one shot clear of American duo Jordan Spieth and Brian Harman.

The 2020 edition was cancelled owing to the coronavirus pandemic.

Up to 32,000 fans will take to the course in Sandwich each day as COVID-19 restrictions ease in England despite a spike in positive cases and the spread of the Delta variant.

"It feels the most normal of any tournament I think that we've played thus far relative to that same tournament in previous years pre-COVID," said Jordan Spieth, aiming to emulate his 2017 Open victory at Royal Birkdale, according to AFP inputs.

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Meanwhile, Oosthuizen, who has been frustrated so far this year in his attempt to add to his only major triumph, a dominant victory in the 2010 Open at St Andrews, started with seven straight pars and accelerated around the turn with seven birdies in 10 holes.

"The perfect round I could have played," said Oosthuizen.

"I didn't make many mistakes. When I had good opportunities for birdie, I made the putts. So just a very good solid round."

But Spieth has rediscovered his form of late with a victory at the Texas Open in April his first in nearly four years.

The world number 13, finished second in this year's two most recent majors, the US PGA Championship and US Open, and is now in contention again.

"Golf is a game played between the ears," added the three-time major champion. "When it's not going great, you can certainly lose quite a bit of confidence.

"That was the first time I've had to really try and build confidence back up, and it takes time."

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Spieth shot up the leaderboard thanks to four consecutive birdies between the fifth and the eighth holes and finished strongly by picking up two more shots at 15 and 16.

After rounds of 66, Canada's Mackenzie Hughes, South Africa's Dylan Frittelli, Americans Stewart Cink and Webb Simpson, and France's Benjamin Hebert are two shots back of the lead.

World number four Colin Morikawa and English trio Justin Rose, Tommy Fleetwood and Danny Willett are among those three under.