Adam Scott and Min Woo Lee have risen before first light to illuminate Australia's British Open chances — but Cameron Smith's hopes of reclaiming his 2022 title were plunged into darkness after a horror opening round at Royal Troon.

Scott and Lee might not have been too thrilled to trudge out of bed in the dead of night to prepare for yawningly early tee times on Thursday, but both made the best of damp, squally conditions that only really improved late in the day as Irishman Shane Lowry grabbed the outright lead with a five-under 66.

Scott, who began with splashing in a birdie straight from the bunker at 7:40am local time, shot a one-under 70, just a stroke better than Lee, who recorded three birdies in his last four holes to get to level par, both right in the thick of the battle.

Lee was the first Aussie out at 7:19am, which meant the Perth ace was up at 4am to prepare after a restless night.

An unsurprisingly sluggish start followed as the 25-year-old bogeyed two of the first three holes, suffered a double bogey after driving out of bounds at the 11th "Railway" hole, but finished like a champ, with birdies from 14ft at 15, 8ft at 16, and 10ft at the last.

In the group behind, Scott, two days after his 44th birthday, opened his 24th successive Open bid with his spectacular splash-in, feeling it was the launch-pad for a "very solid" round which persuaded the 2013 Master he could again contend for the Claret Jug after three previous top-five finishes.

"My game is finally in some decent shape where I feel like I'm controlling the ball well," Scott said.