Jason Day, the 2015 PGA champion and a two-time runner-up at the US Open, has withdrawn from this year's Open at Shinnecock due to a bad back. 

The 38-year-old Australian was wincing in pain while warming up on the driving range. Opening on the back nine, he shot 7-over 42 and after making a triple bogey on number one, he climbed into a golf cart and left the course.

Day opened the season with a tie for second at the American Express and finished 12th at the Masters, but has struggled since.

He has finished second in the three majors he has not won — most recently in the British Open in 2023. His second-place finishes at the US Open came in 2011 and 2013 and he was runner-up at Augusta in 2011.

Earlier, Adam Scott rose to the occasion to be the leading Australian as Shinnecock bared its teeth early in the weather-hit first round.

A two-hour fog delay kept the field waiting before Scott ground out a first-round three-over-par 73 playing his milestone 100th consecutive major championship.

American Sam Stevens snared the clubhouse lead with a two-under 68 as the world's best players battled hard to deal with one of the sternest tests in golf.

Of the other Australians out in the morning, Lucas Herbert carded a four-over 74 and his LIV Golf captain Cameron Smith a 75.

Smith's round was blighted by a dreaded triple-bogey six at the par-3 seventh hole, when the former British Open champion needed two shots from a bunker and then three-putted.

Min Woo Lee has an afternoon tee slot.

AP