Japan's great golf hope Hideki Matsuyama has revealed he feared he would miss the Tokyo Olympics when he tested positive for COVID-19.

The Masters champion pulled out before the second round of the Rocket Mortgage Classic in Detroit on July 2, and the 29-year-old has not played competitive golf since, missing out on the Open Championship.

He has also not had a top-20 finish since landing green jacket glory at Augusta National in April, slightly dampening hopes of a home gold medallist at the Kasumigaseki Country Club, where the men's tournament begins on Thursday.

Matsuyama hopes a strong mental approach can stand him in good stead as he returns to a course that holds fond memories for the 29-year-old.

It is where he won the 2010 Asia-Pacific Amateur Championship, securing him a first ticket to The Masters and serving as a springboard for his professional career.

"To be able to represent Japan and play in my home country and a home Olympics, this is probably the first and last time I'll be able to do that," Matsuyama said in a news conference on Tuesday.

"Three weeks ago I got tested positive for COVID-19 and wasn't really sure I'd be able to make it to this stage here. Now I'm here and I'm very happy to be able to be here.

"I tested positive for COVID for about 10 days in duration. During that time I was unable to practise, but once I got back to Japan I started practising.

"Hopefully I'll be able to be in the best form possible for the event this week."

Matsuyama said he was "very happy" to test negative ahead of the Olympics, and the significance of the venue is not lost on him.

"In a way, Kasumigaseki has been the place and catalyst for me to progress and grow," he said. "Hopefully I can do the same this week and move on to another level.

"Since my Masters win, I haven't had the best results so far this summer, so I'm a little bit nervous, but I'm really looking forward to it. I think it's going to be fun and I'm going to try my best to do well.

"I'm going to try to overcome any physical deficit with the mental side."

With his golf commitments, Matsuyama said he had found little time to watch fellow Japanese competitors from other sports in the Games, although he has been keeping tabs on their success in the medals table, with the hosts challenging near the top.

"Hopefully I can follow their footsteps and be in a position to win a medal as well," he said.