Updated

Southampton, Bermuda (SportsNetwork.com) - U.S. Open champion Justin Rose shot 4-under-par 67 on Tuesday to grab a 2-stroke lead after the opening round of the PGA Grand Slam of Golf.

PGA Champion Jason Dufner carded a 2-under 69, Masters winner Adam Scott shot 1-under 70 and defending champion Padraig Harrington stumbled to a 3-over 74. Harrington replaced Phil Mickelson in the four-man field after the British Open champion withdrew due to a scheduling conflict.

Rose, Dufner and Scott, all first-time major champions in 2013, were tied for the lead at 3-under entering the par-3 16th, where Scott's tee shot landed in a greenside bunker and settled inches from its lip. The Australian then blasted out short of the green, eventually settling for a double bogey.

"It was impossible to get it near the hole," Scott said of his bunker shot. "I was trying to hit it 50 feet long up near Justin's ball, but misjudged it a little bit and it came out so soft. Went under the ball somehow, I don't really know. I wasn't expecting that to feel like that. I was just playing for bogey to hit it up there near Justin's and 2-putt."

The 16th also proved difficult for Dufner, who left his tee shot short of the green and tripped to a bogey, allowing Rose to take the outright lead with a par.

Rose then birdied the 17th to move ahead by two, and the margin held when all four players parred the last.

"I felt like I didn't really play my best today, but I kept the ball out of some really bad spots out there on the golf course," said Rose. "I felt like I putted really well today."

The tournament will be decided Wednesday with another 18 holes at Port Royal Golf Course.

Harrington, who finished runner-up at this event in 2007 and 2008, saw his title defense get off to a rocky start on Tuesday. The three-time major winner birdied the par-5 second, but he stumbled to consecutive bogeys from No. 4 and never fully recovered.

Like Scott, Harrington double-bogeyed the 16th after finding the Atlantic Ocean off the tee. He also bogeyed Nos. 9 and 14 to negate birdies at the seventh and 17th.

"I played like stale golf, tired golf," Harrington admitted. "Definitely hitting the ball better than that, and just decisions and things like that, I just kind of look at it and you know, just played probably too many events and I feel it's time for a break."

The trio of 2013 major winners breezed past Harrington in the early going, as Rose, Dufner and Scott each posted four birdies over their first eight holes. Rose then stumbled to a bogey at the ninth, leaving Scott and Dufner tied for the lead at the turn, and the jostling continued during the inward stretch.

Birdies at Nos. 10 and 12 briefly pushed Rose ahead, but the Englishman bogeyed two straight from the 13th to again drop into a tie with Dufner and Scott.

Dufner began his inward nine with bogeys at the 10th and 14th and a birdie at the 13th, while Scott posted four straight pars and a bogey over that span.

"Everybody kind of started off pretty good on the front nine and then back nine didn't go quite as well for most of us," said Dufner.

NOTES: Rose and Nick Faldo (1996) are the only players from England to compete in this event ... Scott is the first Australian golfer to play in the PGA Grand Slam of Golf since Geoff Ogilvy in 2006 ... Last year, Harrington closed with a 4-under 67 to defeat 2012 U.S. Open champ Webb Simpson by a single stroke ... The defending champion of the PGA Grand Slam of Golf receives the initial invitation if a current major champion is unable to compete.