Tom Kite, Dick Mast, Don Pooley, Jim Thorpe and Rocky Thompson are all tied for second place, one shot back.
Jack Nicklaus, making his first competitive start since July because of an ailing back, opened in 1-over 73. The four-time Tradition winner made five birdies, four bogeys and one double Thursday on the course he designed at the Superstition Mountain Golf & Country Club.
Doyle, who was an amateur legend in Georgia before turning professional at the age of 46, is in search of his first victory of the season and his third different major title. He won the Senior PGA Championship in 1999 and the 2001 Ford Senior Players Championship. Only Nicklaus has won all four major titles on the Senior Tour.
The reigning Senior Player of the Year shot matching nines of 3-under 33, with four birdies and one bogey on each half.
I like fast greens and these are quick, said Doyle, who added the course seemed to play shorter than the 7,225 yards listed on the card. If I was hitting a lot of 5-, 6-irons, I might have some trouble trying to hold the greens with my low-ball (trajectory).
I had some 8s (irons) on down (for approach shots), or at least some 7s (irons) on down. So, I feel like I can go at the pins aggressively.
Doyle made a pair of birdie putts from 10 feet and another from six. He also chipped in from 20 feet for birdie at the par-3 eighth and got up-and-down from a bunker for birdie at the par-5 second.
Kite, the 2000 Tradition champion, started quickly on the back nine. He birdied four of his first five holes. And though he slipped with bogeys at the 15th and 18th, Kite added a pair of birdies to his card on the front.
I was rockn and rolln early on the back nine, said Kite, who already has two wins on tour this season. The back nine is a couple of hundred yards shorter than the front, so you gotta get your licks in on the back.
It was just a phenomenal day for scoring. We dont know how difficult this golf course can play, when the wind starts kicking up; we may find out the next couple of days.
Defending champion Doug Tewell is five back after at 1-under 71. He won last year's event at the Golf Club in Desert Mountain in Scottsdale.
Full-field scores from The Countrywide Tradition