AP photo by Charlie Riedel / Li Haotong tees off on the 10th hole at TPC Harding Park during the second round of the PGA Championship on Friday in San Francisco.

SAN FRANCISCO — TPC Harding Park is renowned for producing champions who are among the all-time best in golf. 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 shot a 5-under-par 65 on Friday and became the first Chinese player to lead after any round of any major tournament.

Surprised? So was he.

Li was in China as the coronavirus pandemic shut down golf in mid-March. He returned three weeks ago and missed the cut at the PGA Tour's Memorial Tournament, then tied for 75th in a 78-man field at a World Golf Championship last weekend 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 63 in the final round of a major. He also was so disengaged during his Presidents Cup debut this past December that he was benched for two days.

Still young, often inconsistent, 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 Friday as he moved to 8-under 132 through 36 holes, giving him a two-shot lead over a large group that included — who else? — Brooks Koepka, who is going for a third straight PGA Championship victory.

Much further back was Tiger Woods, who found more fairways but struggled on the greens, ranking 131st in the key putting statistic in the 156-man field. He flirted with the cut line, which was at 1 over, until a birdie on the 16th hole kept him safe, and his 72 put him eight shots behind.

Woods wasn't alone in his struggles. Rory McIlroy, No. 1 in the Official World Golf Ranking for months before losing the top spot this summer, ran off four straight birdies around the turn and gave nearly all of that away with a triple bogey on the 12th hole, three-putting from seven feet once he finally got on the green. He had a 69 and was seven shots behind. Justin Thomas, who went to No. 1 with Sunday's FedEx St. Jude Invitational victory at TPC Southwind in Memphis, also had to rally to make the cut on the number.

Li got as much attention for the logo on his hat: WeChat, the Chinese social media company and one of his biggest sponsors. Li was in the spotlight at Harding Park one day after United States 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?"

some text
AP photo by Charlie Riedel / Li Haotong hits from the fairway on the 10th hole at TPC Harding Park during the second round of the PGA Championship on Friday in San Francisco.

Koepka was more worried about a tight hip than his 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 to post a 68. It's the fifth time in his past eight majors 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."

Also in the tie for second at 6 under were 2015 PGA Championship winner Jason Day (69), 2013 U.S. Open champion Justin Rose (68), Tommy Fleetwood (64), Daniel Berger (67) and Mike Lorenzo-Vera, who closed with a 15-foot bogey putt for a 68.

Two dozen players were separated by five shots at the halfway point, and the 77 remaining golfers in the field included all three Baylor School graduates in the tournament, though all three were far back in the pack. Harris English (71) and Keith Mitchell (72) were tied for 43rd at par in the group that included Woods. Luke List (69) was tied for 58th in the group that made the cut on the number and included Phil Mickelson.

While Mickelson and Woods, with a combined 20 major titles, have been big names in golf for decades, Li is yet another young player whose potential is still hard to gauge.

He is a two-time winner on the European Tour, most recently at the Dubai Desert Classic in 2018, when 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 last year. 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, one of his teammates in Australia. "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."

And when it doesn't? He beat Koepka in the WGC-Match Play last year and reached the round of 16, but that was his last top-10 result in America.

And then there was the Presidents Cup.

Li brought his trainer to be his caddie, and the caddie got lost on the course during a practice round, gave up and headed for the clubhouse. Instead of finding him, Li played the rest of the round out of another player's bag. International captain Ernie Els wound up benching him for two days, playing Li only when he had to. Li lost both matches he played.

"It's been very tough on me, the Presidents Cup, because I didn't play until Saturday," Li said. "So not quite in the Presidents that way, actually. But anyways, good experience."

Another opportunity for a good experience awaits.

Li was seen at the practice range and putting green much of the afternoon, although Golf Channel reported he had gone to his rental home for lunch and a nap. True, there's not much to do when not playing due to the health and safety protocol in place for the pandemic. And he's young enough that energy shouldn't be a problem.

But it sets up Saturday as a critical day, for Li and Koepka and everyone chasing a major championship trophy, something that hasn't been awarded since last July at the British Open.