MacKenzie had all three of his eagles on par-5s, including one on which his 293-yard approach shot landed 8 feet from the hole. He tied a tour record already set three times earlier this year -- by Arjun Atwal at the Buick Invitational, Bubba Watson at the Zurich Classic and Jason Gore at the John Deere Classic.
'I was just hitting it pretty much wherever I wanted to the whole day and had great speed on the greens,' said MacKenzie, who closed his round with the 8-foot eagle putt on the 616-yard ninth. His other eagle came on a 15-foot putt.
'I'm putting with a claw (grip) now and that's probably why I shot 63. I switched the grip because I'm about 180th on the tour in putting and that's my problem,' he said. 'I've got a lot of confidence now that I've switched grips. I actually believe I'm going to make putts now.'
MacKenzie's 63, a career best in his second year on the PGA Tour, set a record for the lowest first round at the 7,472-yard Montreux Golf and Country Club Course and tied the record of three eagles for the entire tournament.
Estes holed out from 86 yards for an eagle and added seven birdies for his 64. Rich Beem celebrated his 36th birthday with some hot putting and a lucky bounce off a rock in a creek to shoot 66, along with three other players.
Estes, a 19-year tour veteran who claimed the last of his four career wins in 2002, had his eagle from the fairway on the 636-yard, par-5 17th. His longest birdie putt of the day was 13 feet, and the only blemish on his scorecard was a bogey on the par-4 third.
'I've played well in stretches the last couple of months, so I knew I could potentially put something together and that's what I did today,' said Estes, who has four top-25 finishes this year, including second at the Shell Houston Open. 'I don't expect to shoot 8 under every day, but I know I can do it.'
Beem, winner of the 2002 PGA Championship, birdied five of the first seven holes then got the lucky break on the par-4 eighth before adding a fifth birdie on the ninth to get to 6-under 30 on the front nine.
'I hit the ball extremely well today, but I putted even better,' said Beem, who has four top-25 finishes this year. He pulled his drive left toward a creek on the 464-yard eighth, the signature hole on the Jack Nicklaus-designed mountain course with a 100-foot elevation drop from tee to green.
'For sure it was going to go in the creek but it hit a rock and kicked down to about 125 yards from the hole in the fairway. It was unbelievable. But hey, when it's your day, it's your day.'