China's Li Haotong putts on the 18th during a practice round ahead of the British Open at Royal St George's Golf Club on July 13. Photo: VCG

The British Open returns after a two-year hiatus caused by the coronavirus pandemic on Thursday with galleries of up to 32,000 fans allowed in to savor a sight of the world's best golfers at the Royal St George's golf club.

Ireland's Shane Lowry will defend the Claret Jug in the 149th Open Championship, but despite the return of play and patrons, COVID-19 still casts a shadow over the final major of the year.

Masters champion Hideki Matsuyama, two-time major winner Bubba Watson and former British Open winner Zack Johnson have all withdrawn after either testing positive for COVID-19 or being deemed a COVID-19 close contact.

Tournament organizers the R&A recently informed players that the championship will "operate under strict government oversight," with guidelines which prohibit players from going to bars, restaurants and supermarkets during tournament week.

They also have to stay in either approved hotels or private accommodation, which can be shared with up to four members of their team, but not other players.

"I don't have my full team here this week. I don't have my trainer, don't have my chef," said four-time major champion Brooks Koepka. "The cooking definitely is not as good with me, [caddie] Rick, my physio, and my manager, Blake. We're trying our best, but it's not as good as she would make it."

Spain's Jon Rahm is the bookies' favorite thanks to his scintillating form that saw him claim his first major at the US Open last month and briefly move to world No.1 before being deposed by Dustin Johnson.

Rahm admitted his surprise at the size of the galleries given Britain's series of strict lockdowns and restrictions on foreign travel.

As restrictions are eased due to the successful mass rollout of vaccines, Britain is now experiencing more than 30,000 positive cases a day.

"I did not expect this tournament to be the first one we're going to have full crowds, just because of the lockdown and limitations and all," said Rahm. "I am very excited. We've missed it."

Rahm's fine form continued with a seventh-placed finish at last week's Scottish Open in his first event since his US Open win at Torrey Pines.

But he knows only too well how a coronavirus outbreak can change the course of an event after a positive test forced him to withdraw from the US PGA Memorial tournament in June when leading by six shots.

Tommy Fleetwood can count on home support as he aims to become the first English champion since Nick Faldo in 1992 and believes players are now used to dealing with the complexities of coronavirus protocols.

Rory McIlroy will be hoping there is more luck for Northern Ireland in Sandwich, where Darren Clarke won his only major when the Open was last played at Royal St George's 10 years ago.

The four-time major champion has struggled since returning to links courses in recent weeks, finishing in a tie for 59th at the Irish Open and failing to make the cut at the Scottish Open.