Padraig Harrington posted an 8-under 64 to grab the first-round lead at the KitchenAid Senior PGA Championship on Thursday in Frisco, Texas.

Eight birdies and no bogeys formed the Irishman's stellar round, giving him a two-shot cushion over Katsumasa Miyamoto of Japan, who shot a 6-under 66.

Harrington, 51, made the cut at last week's PGA Championship and tied for 50th, so his game was in great form entering the week at Fields Ranch East, a new course at PGA Frisco hosting its first major championship.

He birdied four holes on the front nine and four on the back, including a chip-in birdie at the par-4 10th.

"I had only, I think I had 170 yards into the wind, I hit a 7-iron that came up probably six yards short in the fringe and I just had to chip it over the collar and I chipped it in," Harrington said. "So there -- it did a 360 too. So there was the highlight."

Harrington also made a 35-foot putt for his first birdie of the day at the par-4 second.

"In some ways the reason it was an easy 64 is because when you're playing with somebody like Rocco (Mediate) there's always a bit of chat and there's always a bit of fun going on, so you're quite relaxed," Harrington said. "And that really does make a difference to how you feel about your shots and things like that."

Harrington already has a senior major title in his pocket, the 2022 U.S. Senior Open. That was his first of four wins on the 50-and-older circuit, though he's yet to break through in 2023.

Miyamoto was happy with his 66, which included a 50-foot par putt that dropped at No. 15. The 50-year-old is a veteran of the Japan Golf Tour and rarely played in the United States.

"I started with the birdie, birdie, birdie, so nice rhythm," Miyamoto said. "First tee shot very nervous, but make a birdie, so kind of relax. This course is really tough, the rough is tough. I never seen beautiful course, beautiful and tough and very nice course. I think best in the world."

Adilson da Silva of Brazil, who had a bogey-free, 5-under 67, is tied for third place with Phillip Price of Wales.

Tied for fifth at 4-under 68 are seven players: Stewart Cink, Alex Cejka of Germany, Charlie Wi of South Korea, Richard Green of Australia, Miguel Angel Jimenez of Spain, Robert Karlsson of Sweden and Thomas Bjorn of Denmark.

Defending champion Steven Alker of New Zealand opened with a 2-under 70. Bernhard Langer of Germany, who won in 2017, shot a 1-under 71. With one more victory he can break a tie with Hale Irwin (45 victories) for the all-time PGA Tour Champions wins record.