Collin Morikawa, last year's PGA Championship winner, fired a six-under-par 66 to seize the early lead Thursday before thunderstorms wiped out play for the day in the opening round of the US PGA Memorial tournament.

The 24-year-old American, who shared eighth last month at Kiawah Island in defending his major crown, fired seven birdies against a lone bogey to grab a one-stroke lead when competition was halted for lightning at Muirfield Village in Dublin, Ohio.

The first round was set to resume at 7:30 a.m. (1130 GMT) Friday with six players in the field of 120 yet to tee off.

Morikawa, who began on the back nine, birdied the par-3 12th and followed with back-to-back birdies at 14 and the par-5 15th before stumbling with a bogey at the 18th.

He responded with birdies on the first three holes and another at the par-5 fifth, then closed with four pars to stand one stroke in front of compatriot Adam Long.

Morikawa, who won a Covid-19 replacement event at Muirfield Village last year the week before the Memorial, took advantage of the rain-softened course.

"It was definitely the rain," he said. "The greens were soft enough and they're receptive. But you have to hit the fairway. Out here, wet rough, it's not going to help when the rough is pretty long."

A pack on 68 included Canada's Nick Taylor, Spain's Rafa Cabrera Bello and Americans Xander Schauffele and Bo Hoag.

American Matt Kuchar withdrew with a left forearm injury while Australian Jason Day pulled out before the round began with a back injury.

Morikawa was happy to see spectators after winning last year when they were banned.

"It's so good to see people," said Morikawa. "Since fans have been coming back, like they're the life, they kind of bring all the energy. It's great to see when you hit a good shot and they clap and you can see their excitement, because it makes you just want to go make that putt even more."

'It fits my eye'

Having a course where he enjoys attacking helps as well.

"It fits my eye off the tee," Morikawa said. "I feel like I'm hitting kind of a lot of 9-irons, 8-irons and 7-irons and that's kind of what I've based my game on the past couple years. When I'm able to put those irons in my hands I feel like I can attack pins, I can be smart and give myself maybe some closer birdies than other guys.

"We rolled in a few today and just got to keep that up."

Morikawa changed the grip on his putter for this week but kept the same blade he used to win at Muirfield Village last year after trying changes earlier this season.

"Overall, it's a putter that I've used before, I feel comfortable with," he said. "I just wanted to go back to a blade because I've putted with a blade my entire life.

"Why not just go back and figure out the things that I've been working on and forget about the stroke, forget about the putter, just try and make the putt."