Woods eyes up a birdie at the first..

Champ Brooks Koepka has a chance for a birdie on the second but has to settle for a par - he's still at five under.

Ireland's Shane Lowry, who picked up a birdie at the first, also settles for par and is three under for the tournament.

Jason Day after a trilogy of pars in his opening three holes birdies the fourth to go to six under, alongside Tommy Fleetwood who is back at the ranch with leader Li Haotong (-8).

Iain Carter
BBC Sport commentator on BBC Radio 5 Live Sports Extra

The four-time major winner needs a big day today - and he knows it. He didn't have one yesterday, he didn't get the fast start he was looking for, but he's still very much in this US PGA Championship.

A level-par 70 yesterday, and you would think he needs to be in the red figures.

Woods (-2) smacks it straight as a plumb line from the first tee, McIlroy's (E) ball bounces past his partner's as does the ball of world number one Justin Thomas(+1).

Palatable start for the trio.

Tony Finau, with six top 10 finishes in majors, ha picked up two birdies in his first four holes to go to five under.

Five under is the new four under.

Tiger Woods and Rory McIlroy up in one minute.

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Anthony Wall
Two-time European Tour winner on BBC Radio 5 Live Sports Extra

That's a good score for Robert MacIntyre and just shows you the quality of European golf, 67 on a Friday.

He'll want to make the cut. I remember my first US PGA at Medinah and Ben Curtis birdied the last to knock us all out. It was the last group on a Friday and it was just a killer.

All you want to do is make the cut and play at the weekend. For him, he'll be doubly happy to make the cut, and he will go forward because the pressure will be off.

He's very long, very aggressive, and he just loves golf. He's one to watch because he makes it look so easy.

Paul Casey can be someone who produced one great round at a major followed by a rotter, but in San Fran he's just posted a 67 after a 68 on Thursday.

He's on five under for the championship and now in a five-way tie for third after Brooks Koepka picked up a birdie at the first.

Scotland's Robert MacIntyre has just posted a three-under 67, leaving him level par for the championship. Good effort by the left-hander in just his second major and may just be enough for him to make the cut.

The 24-year-old finished in a tie for sixth at last year's Open before securing last year's Rookie of the Year award for the European Tour.

Image source, Reuters

Defending champion Brooks 'Threepeat' Koepka gets his second round under way with a decent drive.

He produced a round of four-under 66 on Thursday. A nice unspectacular round.

Anthony Wall
Two-time European Tour winner on BBC Radio 5 Live Sports Extra

Tommy Fleetwood's moved up 46 spots, and that’ll improve later. That’s a huge move, and if he keeps in that form, he’ll be tough to beat because we know Tommy, he won't back away.

He's good friends with Shane Lowry and I honestly felt he thought it was Shane's time [at the 2019 Open]. All the crowd was willing Shane, so it was difficult for Tommy. A couple of times Tommy has been close, where the leader has just been too good. This might be his chance where he's the leader and he might stretch [ahead].

The projected cut is at level par, and a handful of big names are set to say farewell to Harding Park - they include Bubba Watson, Sergio Garcia and Phil Mickelson.

It looks like Rickie Fowler will miss the cut after finishing on two under, which included a double bogey on the par four sixth when he stubbed his putter in attempting to tap in. The ball travelled an inch.

Gloriously ugly.

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Andy McNamara: DeChambeau is forcing this too much. He needs to be more savvy if he wants to win a major. Just smacking a ball as hard as you can won’t always work. Look at Woods at Hoylake in 2006.

21:36 Brooks Koepka, Gary Woodland, Shane Lowry (Ire)

21:47 Jordan Spieth, Dustin Johnson, Justin Rose (Eng)

21:58 Tiger Woods, Rory McIlroy (NI), Justin Thomas

22:26 Mike Lorenzo-Vera (Fra), Marty Jertson, Tom Lewis (Eng)

Here's Tommy Fleetwood after hitting the lowest round of the championship so far.

"Yesterday I had a decent score going then had a bad couple of holes. But level par wasn't a bad score.

"I feel like my game is improving day by day, and today I hit a lot of good golf shots. With the wind, an average shot actually becomes a good one. I hit a lot of fairways and that makes it easier around this course.

"I'm not going to say I'm playing the best I've ever played, or I feel the sharpest I've ever felt. But it's a major championship and I've just shot a good score, so I can't be far off."

BBC Radio 5 Live Sports Extra

The US PGA coverage is under way on BBC Radio 5 Live Sports Extra.

Tune in folks!