Australia's dwindling hopes of British Open success at Royal Portrush lie solely in the hands of a sleep-deprived Marc Leishman after a wretched day for the gold 'n green challenge on the Dunluce links.

The experienced 'Big Leish' was the only Aussie out of a starting field of nine to make the cut on Friday, with former champion Cam Smith and 25-time Open veteran Adam Scott suffering particularly disheartening days.

Leishman was let off the leash after being frustrated by the slow pace of play on the opening day - and the result was by far the best round from any of the battalion as he shot a three-under 68 to make the weekend on one under, the only Aussie all week to be in the red.

With the cut having looked set to be at two over, Jason Day, runner-up two years ago, had dug deep to conjure a birdie on the penultimate hole, with a booming drive and 90ft chip stone-dead, to get to what he hoped would be the required mark.

But, alas, the Queensland ace was left missing the boat on two over by just a shot as late afternoon conditions improved. Poor old Day must have still been harbouring hope at nearly 9:30 at night when the cut line was finally established at one over.

Leishman, the lone survivor, has his work cut out, nine shots behind inspired leader Scottie Scheffler, but at least he enjoyed a much more fulfilling day - one that started at 4am before he was the first to tee off at 6:35am - than the one he endured on Thursday.

The 41-year-old Victorian had bemoaned the interminable first round, complaining he felt like he'd been out there 'for about 12 hours' amid constant snarl-ups through slow play.

But freed up among Friday's very first group out, the LIV Golf veteran, two-over-par overnight, enjoyed five birdies in the first dozen holes to move momentarily to within a shot of the early lead.

Two bogeys at the next two holes, including a horrid shank off the tee at 13, checked his magisterial progress but a decade on from his 2015 St Andrews near-miss when beaten in a play-off, Leishman, three times an Open top-10 finisher, was able to come through with a smile.

'I was obviously pretty frustrated last night when I came in here,' he told reporters, apologetically.

'I always say to my wife, 'if I've had a bad day on the course, just give me 10 minutes, and I'll be good' ... I think you got me about the eight-minute mark!'

Having got up at 4am - 'I set the alarm as late as possible, I love my sleep,' he sighed - Leishman spent the rest of Friday after his round watching his rivals' travails on TV. 

'l'll probably have a pint or two of Guinness and enjoy my afternoon,' he had noted.

There was nothing enjoyable for Scott out there, though, on his 25th consecutive British Open and 97th straight major appearance.

Having started out as joint-leading Aussie alongside Smith, after their first-round 72s, Scott had been hoping to celebrate his eve-of-tournament 45th birthday with another stirring crack at the Claret Jug.

But he had the most miserable day, making three double bogeys at the short third, the par four 11th where he drove into the bushes, and the par three 16th, before a bogey at the last left him with a 79 - his worst round at the British Open since his 82 at Royal St George's 22 years ago - and a tournament total of nine over.

Smith fared little better, the 2022 champion shooting a 78, coughing up six bogeys and a double, with his lone birdie coming at the 17th as he ended on eight over.

Min Woo Lee (73, five over for the championship), Lucas Herbert (72, four over), Curtis Luck (70, eight over) and Ryan Peake (73, eight over) didn't make it either.

Early starter Elvis Smylie (70, three over) had a long fruitless wait, hoping the fairly mild weather might worsen to allow him to scrape in.