History was firmly against all but six players as they attempted to claim major championship glory in the 121st US Open at Torrey Pines.

With the field separated by just nine shots following the halfway cut, Saturday's early starters still no doubt harboured ambitions of playing their way back into contention in San Diego.

However, 23 of the last 25 US Open champions were at or within two shots of the lead after 36 holes, with 24 of the last 25 inside the top six at the same stage.

Such statistics pointed to the winner coming from joint leaders Richard Bland and Russell Henley, nearest challengers Louis Oosthuizen and Matthew Wolff or Bubba Watson and pre-tournament favourite Jon Rahm.

But England's Paul Casey showed what could be possible as he covered the front nine in just 31 shots thanks to birdies on the second, fifth, eighth and ninth.

The back nine was a scrappier affair with three birdies and three bogeys, but the resulting 67 equalled the lowest score of the week so far.

"Conditions were perfect for golf, slightly overcast, slight little wind," Casey told Sky Sports. "I don't think the course is any different (from the first two days). I think we've seen today some more accessible pin positions, a couple of tees have been moved up.

"Certainly nine is now reachable for almost everybody in the field and 18 is definitely reachable for everybody in the field.

"I drove it brilliantly the first two days and didn't really capitalise on how I struck it. I didn't have the speed down with the putter and today was the first day where I felt like I had touch on these greens."

England's Bland only won his first European Tour title at the 478th attempt five weeks ago, while Henley's last PGA Tour title was four years ago.

Bland began the week as a 500/1 outsider and 115th in the world, remarkably the same ranking Phil Mickelson held before he became the oldest major champion in history by winning the US PGA, eight days after Bland's victory in the British Masters.

The 48-year-old, who is the oldest player to lead or share the lead after 36 holes in US Open history, was largely unknown in the United States before this week, but quietly fancied his chances after seeing the course.

"I was coming here off a couple of good results, a win and a third in Europe," Bland said. "I've been driving the ball well for five, six weeks now, which is the cornerstone if you're going to put a fight up for a US Open.

"When I saw this place on Monday, it kind of set up to my eye. It's all there just straight in front of me, and that's the kind of golf course I like. There's nothing kind of jumping out and grabbing you or anything like that."