Morikawa felt good vibes from an old putter and posted a six-under-par 66 in rain-softened conditions at the Memorial to grab a one-shot lead over Adam Long among early starters, with Xander Schauffele in the group two shots behind.

The weather was bad enough that the first round was suspended twice, with only half the field – and no Australians – finishing.

For Morikawa, the name of the tournament is different, too. He won a playoff at Muirfield Village last year in the Workday Charity Open, a one-time event to replace the pandemic-cancelled John Deere Classic.

But there's a comfort level at the course Jack Nicklaus built, no matter how much it has been renovated and reshaped. And it was noisy on Thursday as the tournament has let at least 25 per cent capacity of fans on the course.

Jon Rahm is the defending champion at the Memorial and faced a far stronger test. Nicklaus knew he was going to be redoing the fairways and greens, so he let them go for the Memorial and conditions were as tough as a US Open.

Rahm did OK in the soft conditions with a 69, tied with British Open champion Shane Lowry, Justin Thomas and Rickie Fowler, who needs a runner-up finish to move into the top 60 in the world ranking and avoid US Open qualifying on Monday.

RIGHT: Morikawa won the Workday Charity Open at Muirfield Village last year. PHOTO: Gregory Shamus/Getty Images.

Jordan Spieth, Bryson DeChambeau and Rory McIlroy didn't make it past a couple of holes before the weather stopped everything.

All six Australians had afternoon tee times so also only played a few holes.

Marc Leishman was two under through five holes and just four behind Morikawa.

Matt Jones and Cam Davis were tied for 20th at one under through four and five holes respectively, with Adam Scott even par after two.

Lucas Herbert was even after one hole, with Cameron Smith one over after his opener.

Jason Day withdrew with a back injury, meaning the former World No.1 will almost certainly also miss this month's US Open after failing to regain his place in the top 60, which offers automatic entry.

Players were to return on Friday morning to finish the first round, and then right back out for the second round.

The forecast was better for the rest of the week, and darkness doesn't set in until about 9pm.