DUBLIN, OHIO - JUNE 05: Jon Rahm of Spain plays his shot from the 18th tee during the third round of The Memorial Tournament at Muirfield Village Golf Club on June 05, 2021 in Dublin, Ohio. (Photo by Sam Greenwood/Getty Images)

Golf's world #3, Jon Rahm, was forced to withdraw from the Memorial tournament in Ohio after testing positive to COVID-19 at the end of the third round.

The Spaniard had tested negative for four consecutive days before returning a positive test from a sample collected on Saturday morning.

The US PGA Tour outlined in a statement that it had informed Rahm that he had come into close-contact with someone confirmed to have COVID-19. Rahm was asymptomatic but was informed of the positive test just after finishing his third round.

Rahm shot an impressive eight-under par for a score of 64 in the third round, putting him six strokes ahead of his competitors heading into the last round at 18-under par, which matched the largest 54-hole lead in Memorial history with Tiger Woods' performance in 2000. 

Rahm was also looking to join Woods as the only back-to-back winner of the tournament, after his success at the Memorial in 2020.

In 2020, Rahm pocketed $2.16 million from his victory at the same event, but in 2021 he will receive nothing due to his unfortunate, late diagnosis.

Rahm expressed his disappointment in a statement to his fans on Twitter.

"I'm very disappointed in having to withdraw from the Memorial Tournament. This is one of those things that happens in life, one of those moments where how we respond to a setback defines us as people," Rahm wrote.

"I'm very thankful that my family and I are all OK. I will take all of the necessary precautions to be safe and healthy, and I look forward to returning to the golf course as soon as possible."

Rahm's departure for the final round opened the door for Patrick Cantlay and Collin Morikawa to battle it out for the trophy, with Cantlay winning in a playoff after both finished 13-under par for the tournament.

Despite being thrust into tournament leadership - and eventually winning the event - Cantlay expressed his feeling to the media regarding Rahm's positive diagnosis.

"It’s obviously really disappointing. It’s the worst situation for something like that to happen," Cantlay told media.

"He played awesome today and it’s just really a shame. It’s unfortunate. I guess we knew that this was a potential lurking out there even when we came back to golf. It’s just extremely unfortunate."

Rahm is now in isolation until at least June 15th, and will face an uphill battle to be able to compete in the US Open at Torrey Pines starting on June 17th.