SAN FRANCISCO – Harding Park is renowned for producing champions who are among the best in golf, from Byron Nelson to Tiger Woods, and a long list of Hall of Famers and major champions in between.

Halfway through the PGA Championship, Li Haotong delivered his own footnote in history.

With five birdies through 10 holes, and eight tough pars down the stretch, Li had a 5-under 65 on Friday and became the first Chinese player to lead after any round of any major.

Surprised? So was he.

Li was in China when the pandemic shut down golf. He returned three weeks ago and missed the cut, and then tied for 75th in a 78-man field in Memphis.

"I didn't even [think] I could play like this ... got no confidence," Li said. "Probably it helped me clear my mind a little bit."

His credentials are all over the map. Li is one of six players to shoot a 63 in the final round of a major. He also was so disengaged in his Presidents Cup debut that he was benched for two days.

Still young and inconsistent but forever fearless, Li is capable of just about anything on a big stage in golf.

A 25-year-old full of energy and antics, he was bogey-free and at 8-under 132 after two rounds, giving him a two-shot lead over a large group that included Brooks Koepka, the two-time defending champion.

Much farther back was Woods, who found more fairways but struggled on the greens, ranking 131st in the key putting statistic against the 156-man field. He flirted with the cut line until a birdie on the 16th kept him safe, and his 72 put him eight shots behind.

Woods wasn't alone in his struggles. Rory McIlroy ran off four straight birdies around the turn and gave nearly all of those strokes away with a triple bogey on the 12th hole, three-putting from 7 feet once he finally got on the green. He had a 69 and was seven shots behind. Justin Thomas, the world's No. 1 player, also had to rally to make the cut on the number.

Li got as much attention for the logo on his hat — WeChat, a Chinese social media company and one of his biggest sponsors. Li was in the spotlight at Harding Park one day after President Donald Trump signed executive orders on a vague ban of WeChat and TikTok in 45 days.

Just as unclear was whether Li was aware of the development.

"I don't know," he said. "Who knows?"

Koepka was more worried about a tight hip than a nagging left knee, and he had a trainer come out to stretch and twist him three times along the back nine. It loosened him up enough for Koepka to post a 68. It's the fifth time in his past eight majors that he has gone into the weekend within three shots of the lead.

"I felt like I probably could be 10 [under] right now," he said. "Hit a lot of good putts, just didn't go in. ... But driving it pretty well. Iron play, I'm pretty pleased with. You know, I like where I'm at."

Li is a two-time winner on the European Tour, most recently in 2018 at the Dubai Desert Classic, where he rallied down the stretch to beat McIlroy by one shot.

He was sensational in the final round of the 2017 British Open at Royal Birkdale — only five other players have shot a 63 in the final round of a major. But he had a terrible week in his Presidents Cup debut at Royal Melbourne in December. When he first came to America, he made fast friends on the developmental tours with his constant laughter, engaging personality and aggressive play.

"He's got the arsenal to take it low," said Adam Scott, his teammate at Royal Melbourne. "But we don't see that kind of consistency out of him, and that probably matches his personality a little bit. He's young, though, and that's the kind of golf he plays. He plays pretty much all guns blazing, and when it comes off, it's really good."