Top-ranked Rory McIlroy and his fellow 2014 major champions charged into contention on day one of the PGA Championship, each seeking the first two-major season since Padraig Harrington in 2008.
In the feature pairing of the opening round at Valhalla that united the year's major winners, reigning British Open champion McIlroy fired a five-under 66 to seize a share of second, one stroke off the pace of Britain's Lee Westwood and Americans Ryan Palmer and Kevin Chappell.
McIlroy, the 2011 US Open and 2012 PGA Championship winner, is the clear favorite after taking the Claret Jug last month at Royal Liverpool and his first World Golf Championships title last weekend at Akron.
"One of the big things for me in majors is to get off to a good start," McIlroy said. "I've been able to do that. "You look at the three wins I've had and I've started really well in each of them. It's important and it's great to get off to another one today."
American Bubba Watson, who won his second Masters green jacket in three seasons back in April, and Germany's Martin Kaymer, a runaway winner in June's US Open at Pinehurst, each opened on 70 at the 7,458-yard layout.
"I'm playing good. I like where I'm at," Watson said. "It was a solid round. It was a good start. I thought under par was decent."
Kaymer, the 2010 PGA winner who opened a huge lead after 36 holes at Pinehurst two months ago and took a wire-to-wire victory, was methodical and pleased with his start.
"I played very consistent. I didn't make many mistakes," Kaymer said. "I only made two birdies and they were birdies from four feet and six feet. So unfortunately I couldn't make a lot of putts from any distance."
McIlroy, trying to become the first back-to-back major winner since Harrington's 2008 British Open and PGA triumphs, said having his fellow major champions alongside did not distract him.
"I doesn't affect me. I try not to pay attention to what the other guys are doing," McIlroy said. "If I stick to my game plan and I see them hitting a different club, that's not going to affect me."
Watson did notice McIlroy's sizzling start, which included a run of four birdies in a row starting at the 12th after he opened the back side double bogey-bogey.
"He's playing great right now," Watson said. "He's probably playing the best of anybody. Very solid. Very in control of everything. Where he made a bogey and double bogey, he didn't get upset.
"He knew he was playing good enough to make birdies. Then he did. Pretty good."
McIlroy, going for his third win in as many starts, could become only the third man in the past quarter-century to win the week before a major and then take the major, following Tiger Woods in 2007 at the Akron WGC and PGA Championship and Mickelson in 2006 at a PGA event in Atlanta and the Masters.
