Cameron Smith has missed the cut as Adam Scott was fighting desperately to stay in touch during another rough and tumble round at the US Open in Massachusetts.

Smith's hopes of challenging for a first major championship bit the dust at Brookline after a second disappointing round with Australia's world number six following up an opening 72 with a frustrating 74.

He slumped to six over par for the tournament, ensuring he would miss the halfway cut this weekend.

Playing in his 84th consecutive major, the former world number one Scott continued to be Australia's brightest ray of light but will need a weekend charge after a three-over 73 left him seven shots adrift of clubhouse leader Collin Morikawa.

Starting on the back nine, Scott mixed two birdies, with two bogeys to remain in red numbers at the turn.

A double-bogey five on the second, his 11th hole, threatened to derail Scott before a bounce-back birdie on the fourth steadied the ship.

However, Scott copped a nasty break when he almost holed out for eagle on the next, only for his ball to ricochet off the pin and spin several metres away from the hole.

Two late bogeys compounded his woes and left the 2013 Masters champion in a tie for 38th, with little-known countryman Todd Sinnott.

A sectional qualifier in Japan, the 439th-ranked Sinnott posted his second successive 71 to impressively survive the cut at two over, the same score Marc Leishman was on with two holes of his round remaining.

And two weeks after his sister Minjee Lee won her second major at the US Women's Open, Min Woo Lee also looked set to secure a weekend tee time after a late rescue act in his second round.

Lee eagled his penultimate hole, the eighth, sinking an 18-footer that ensured he battled back to three over for the tournament after a level-par round of 70.

However, the tournament is over for Smith and fellow Australians Lucas Herbert and Jed Morgan.

Smith had his work cut out after a difficult opening round and his hopes of a fast start were quickly scuppered on Friday morning.

The Queenslander found the thick, rough stuff in front of the green at the par-three second, and swished angrily at the grass after failing to get within 30 feet with his second shot.

After a bogey there, his mood was hardly improved with further dropped shots at the fourth and sixth, leaving him with a mountain to make it to the weekend.

But it only got worse: A wayward drive at the 10th and the failure to extricate himself from a tough greenside lie at the 15th led to two more bogeys.

A tee shot to five foot, at the par-3 16th, eventually earned Smith his first birdie in 23 holes but it was too little, too late, with the cut line projected to be at four over.

Herbert crashed to 13 over, with a horror 79, while Morgan ended at 16 over after following up his disastrous opening 82 with a 74.

Chasing the third leg of a career grand slam, Morikawa grabbed the solo lead at five under, with a 66, the low round of the day.

He led fellow American Hayden Buckley (68) and Spain's defending champion, Jon Rahm (67), by a shot.