Tom Kim defied jet-lag and just six hours of sleep in two days to shoot a three-under par 67 as the Asian Games golf began on Wednesday, while defending champion Taichi Kho had a hole-in-one.
South Korea's Kim flew in from the Presidents Cup to be in a share of seventh place on his Games debut.
His playing partners in the signature group -- Keita Nakajima of Japan and Kho of Hong Kong shot 68 and 69 respectively.
With three rounds to go on the par-70 Kasugai Country Club layout, the men's individual leaderboard was topped by Wang Wei-hsuan of Taiwan and Japan's Kazuki Higa, who both carded five-under-par 65s.
Only 48 hours earlier, Kim had beaten US Open champion Wyndham Clark 3 and 2 in his Presidents Cup singles, albeit in a losing cause for the Internationals against the United States at Medinah, Illinois.
The world number 32 then jumped on a plane to Japan, needing to cope with the journey and a 14-hour time difference.
"I've had six hours of sleep in the last 48 so I'm hanging in there," Kim told AFP.
"It's nice to be back in Asia. I don't get to come back as much so it's been fun and so far all good," added Kim, a former Asian Tour order of merit winner who has four titles on the US PGA Tour.
"I think on the back nine I started to feel it a little bit, especially playing five matches last week. It's just a lot of golf," said Kim.
"Hopefully I'll get a couple of decent sleeps and try to feel better."
Highlight of the day was Kho's ace at the par-three seventh, where the Hangzhou Asian Games gold medallist was watched by his mother and father.
"The greens are really soft today, I only had 155 (metres) and had to take a lot off a seven iron," Kho said.
"So I just chipped the seven-iron and it looked really good in the air. I actually didn't see it go in the hole."
There is also a team prize at stake, with the aggregate of individual scores counting.
Hosts Japan top the men's standings at nine-under par, with their third player being amateur Taishi Moto, who carded a four-over 74.
"It's a great start," said co-leader Higa.
"Us two professional players, Keita and I, want to lead Taishi so he can play freer."
China are in a share of second on seven-under with South Korea, who know there will be more at stake than just a gold medal.
Should they top the podium the players will be rewarded with an exemption from military service.
"I think about it. It's so tough," said S.H. Kim of the prospect of doing time in the army.
He added: "It would be so exciting (to win gold). I have two years military service (due) so I could stay on the PGA Tour. That's my goal.
"Team gold is easier because we have the players."
Tom Kim added: "A gold medal would be great, but you just want to do well for your country."
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