American Rickie Fowler clubhouse leader on -7
England's Paul Casey -6; Tommy Fleetwood -5
Dustin Johnson starts title defence with +3
Rory McIlroy posts +6, Justin Rose level
7,741-yard course with deep rough - longest in major history
Els -4 (10)
So, who else is in the mix?
One Ernie Els, that's who. The 47-year-old South African is four under through 10, and tied for fifth with Brooks Koepka.
Patrick Reed is one shot ahead, alongside Tommy Fleetwood and Brian Harman.
Westwood -3 (12*)
Image source, ReutersTommy Fleetwood isn't the only Englishman impressing on day one, with the more experienced Lee Westwood also just three shots off the lead.
The 44-year-old recovered from an early double bogey by shooting five birdies, all in his opening nine holes.
Nice and simple, hey Lee? Well, he's found three successive pars since the turn.
James Peacock
BBC Radio 5 live at Erin Hills
The course seems more accessible than it was on the practice days. The weather is good and it’s not often you see players attacking a US Open course like they are today.
Two of the favourites are struggling, though. Dustin Johnson does not look at his best and the highly fancied Spaniard, Jon Rahm, has already lost his temper a couple of times.
Keeping his cool near the top of the leaderboard is England’s Tommy Fleetwood who is one shot off the lead on -5.
He was a guest in the 5 live studio before his US Open debut at Chambers Bay – where he was finished the week as the leading Englishman, tied 27th .
Chambers Bay was a first time venue for this tournament, also highly-criticised, and not dissimilar in its links feel to Erin Hills.
Long way to go, but Fleetwood is making the best of some decent scoring conditions on day one.
Fowler -6 (13*)
Rickie Fowler's scorecard remains flawless as he pars the second, and the American maintains the lead.
Fowler, who started from the 10th, is six under through 13 and looking good in a blustery Wisconsin.
Image source, Getty ImagesUnconfirmed reports on social media suggest a blimp has crashed into the ground near the US Open.
A person was seen parachuting out of it before it slowly landed on the ground away from the course.
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Rahm +3 (12*)
Think I've jinxed Jon Rahm. His bag is feeling the brunt of the Spaniard's frustration again after under-hitting his approach.
The world number 10 is head down, marching towards the green. But he'll have to clip one up to reach it.
He's not happy with that either, landing 10 feet or so short of the pin.
Image source, EPARahm +3 (12*)
Image source, Getty ImagesThe course very much has a links feel to it, as best put by Spain's Jon Rahm...
The 22-year-old said the US Open venue was "like a links golf course on steroids".
"But I think it's US Open, they expect our best," he added.
Rahm certainly needs his best if he's to rescue this round, but is he starting to get to grips with Erin Hills?
After four bogeys on the opening nine, Rahm has collected his first birdie of the championship. It's come at the par-four third and takes him to three over.
Still plenty of big names to go out this evening, so here are a few groups you might want to keep your eye on:
19:36: Bubba Watson (US), Adam Scott (Aus), Sergio Garcia (Spa)
19:47: Henrik Stenson (Swe), Louis Oosthuizen (SA), Charl Schwartzel (SA)
20:09: Jason Day (Aus), Justin Rose (Eng), Rory McIlroy (NI)
Johnson +3 (9*)
Image source, Getty ImagesLet's take a look at the world number one... Although he might rather we didn't.
Dustin Johnson is still three over, despite a birdie at the par-three 16th. But that was sandwiched by bogeys, adding to an earlier double.
A long way to go, but I guess the one softener for Johnson if he does miss the cut is that he can return to newborn son River Jones a bit sooner.
Or RJJ as golfing hacks will refer to him when he's winning majors like his dad.
Worth noting that the forecast for Friday at Erin Hills isn't good, with Thursday by far the best day.
There is potential for rain tomorrow and thunderstorms on Saturday.
How will that impact the scores? Well, I wouldn't fancy hacking around in that fescue when it's wet.
Fowler -6 (11*)
OK, stop it now Rickie. You're making a mockery of what was supposedly one of the USGA's toughest courses.
It's another birdie for the American, who is really putting a marker down on the opening day in Wisconsin.
It could've been more for the 2014 runner up, who two-putted to go six under through 11.
Image source, Getty Images(All US unless stated)
-5 T Fleetwood (Eng)*, R Fowler*
-4 B Harman*, JB Holmes
-3 P Reed, C Hoffman*, M Putman
-2 Y Miyazato (Jpn), T Aiken (SA), B Koepka, B Snedeker, JB Holmes, L Westwood (Eng), E Els (SA), B Grace (SA), J Lovemark
Selected others: -1 M Laird (Sco), M Kaymer (Ger)*,J Spieth*; +1 A Rai (Eng), Alex Noren (Swe), R C Bello
*Tee off from 10th hole
Fleetwood -5 (11*)
Anything Rickie can do, Tommy can do too...
Tommy Fleetwood is playing a hole ahead of the joint leader, and has just carded his third birdie in succession.
The Englishman is soaring, right up to the top of the leaderboard.
Image source, EPAFowler -5 (10*)
"Hit the fairways and you'll be fine..." said those defending the knee-high fescue that makes up Erin Hills' rough.
Rickie Fowler was listening. He sends his tee shot a little over 290 yards into the good stuff at the first - which proves the turn for the American - and makes it onto the green in two at the par five.
Two putts later and Fowler is another birdie up, moving him to five under for the day.
Image source, Getty ImagesThis graphic from the USGA looks like it's come from one of my old maths textbooks, but it gives you a good look at today's greens....
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Holmes -4 (9)
Oh hello, JB Holmes. Where did you come from?
A little ride on the birdie train sees the American depart at frontrunners station, snaffling up strokes as he goes.
It's back-to-back birdies at the eighth and ninth for Holmes, and he takes a four-way share of the lead.
Image source, EPAThere's been a light smattering of applause with every tee shot at Erin Hills so far, but it's hard to tell whether many fans are still to turn up or whether the crowd is just very sparsely spread at this mammoth venue.
Image source, Getty ImagesHarman -4, Fleetwood -4 (10*), Fowler -4 (9*)
What a fantastic start to the US Open it has been for Tommy Fleetwood.
The 26-year-old from Southport has taken a share of the lead with his fourth birdie of the day, easing his way through the par-five 613-yard 18th as he hits the turn.
Brian Harman remains at four under, and Rickie Fowler has also joined the leading pack.
Johnson +3 (6*)
It's been a costly couple of holes for Dustin Johnson.
That's another bogey at the 15th, meaning he has dropped three shots in two holes.
The American escaped the fescue without too many problems this time after sending his tee shot into the edge of the rough, but three putts once on the green.
Image source, EPA