That's some record for the clubhouse leader, Australian Jason Day.

A smooth stroke of the putter from Bryson DeChambeau and it's a birdie on the first - matched by compatriot Rickie Fowler.

Only par for Adam Scott.

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It's not been pretty but Bryson DeChambeau finds the green with his second shot.

The hole: A relatively straightforward opening hole at under 400 yards and with no fairway bunkers. A sole greenside bunker is the biggest challenge on the approach shot.

Seven of the last 11 winners of the US PGA Championship have been first-time major winners:

• 2017 - Justin Thomas
• 2016 - Jimmy Walker
• 2015 - Jason Day
• 2013 - Jason Duffner
• 2011 - Keegan Bradley
• 2010 - Martin Kaymer
• 2009 - Yang Yong-eun

Now, I don't think my colleague Alex Bysouth has posters of world number seven Bryson DeChambeau on his bedroom wall at home, but he's gone to some length to produce this piece on the American whose dedication to becoming the ultimate golfer has seen him go to great lengths.

3,500 calories a day anyone? Imagine what he could put away between Monday and Wednesday in August over here in the UK?!!!

If you're going to choose DeChambeau as your specialist subject for Mastermind then read this.

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We have a new trio who get their challenge under way...

Rickie Fowler finds the rough from the first tee and beefy Bryson DeChambeau goes wild.

What about you Adam Scott?

Down the right and near the trees.

Oh dear.

Tiger Woods, with his best opening round in a major since 2012, was content with his efforts and knows what it will take to be successful this weekend.

"I figured we were going to get favourable conditions early on and it’s going to get more difficult. Some of the pins were on the difficult side. This golf course is all about hitting fairways."

Woods produced a two-under-par 68 and is currently three shots behind leader Jason Day.

Image source, Reuters

Walter Hagen also shares the record for most US PGA wins with Jack Nicklaus - five. Tiger Woods hopes to join them this weekend, although the former world number one hasn't won it since 2007, at the Southern Hills Country Club in Tulsa.

Might it be a Koepka-Thomas finale in San Fran on Sunday afternoon?

Justin Thomas, the last player to win this major before Koepka, beat his rival at the recent St Jude and is the new world number one as you know - and he's as confident as someone who's left their home at 6am on Monday in order to get a seat for their 50% breakfast. Confident.

Before the tournament, the 27-year-old who is looking for his third win of the year and his second major, said:

"My game is in a good place, obviously. I feel really good about everything.

Pray tell JT, why have you only won one major?

"I would definitely say I've underachieved, saying I've only had one so far in my career. I've felt almost getting the second one has been harder than the first one.

"To kind of get into that level, that other level - and to be up into the double digits in majors for a career - you need to start winning some."

Correct.

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

"I found with majors it was playing in the first round of a major. You were just buzzing to get going. There was no better feeling than that.

"They're golfers, they've missed majors, they've missed playing in majors.

"As a golfer you prepare for four majors and having had to wait for six months, you're surely just raring to get going."

Rory McIlroy keeps his nerve for a par at the last. It's a 70 and level par for him.

A decent first round in the end for the man from Northern Ireland after three successive bogeys on the front nine.

McIlroy's putt shoots four feet past the hole, while Woods taps in for par and a 68 after his putt approaches tap-in range.

World number one Justin Thomas ends with a birdie for a 71. Good putt.

Brooks Koepka, looking for a hat-trick of US PGA wins, and Justin Rose have completed their rounds. They went around Harding Park in 66 and are four under for the championship - one shot behind J Day.

Zach Johnson, Xander Schauffele, Bud Cauley, Scottie Scheffler and Martin Kaymer are also in the clubhouse on four under.

Gorgeous iron from Justin Thomas - straight as an arrow - to land the ball about eight feet from the flag.

Tiger Woods is a bit more cautious and has a long putt for an birdie.

Rory McIlroy just about makes the green, but he was in some deep rough tbf.

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Rory McIlroy finds the long grass from the ninth tee, Justin Thomas is in the middle of the fairway and Tiger Woods produces some left-to-right fade with his driver to find safety.

The hole: Converted from a par five for the championship, the final hole on the front nine is also protected by a cluster of fairway bunkers and more up at the green.

But nooo....the ball doesn't break like he expects it too and the ball drifts past. Bogey coming up.

Woods puts plenty of check on his shot, which any snooker fan would appreciate, as he finds himself now within a few feet for par.

It looks like Tiger Woods has found the sand on the right of eighth hole. Hard to tell what the lie is like. Playing partners Rory McIlroy and Justin Thomas are OK.

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Just six miles from the Golden Gate Bridge and the Painted Ladies pictured above...

Steady-hands Rose sinks a 15 footer on the par three eighth for back-to-back birdies with one to play.

He's on four under along with six others. Jason Day is back in the clubhouse as the outright leader on five under.