PARAMUS, August 21, 2014 (AFP) - McIlroy, coming off major victories at the British Open and PGA Championships, fired a three-over par 74 in the first round of the opening event of the US tour's season-ending playoffs at Plainfield Country Club.
That left the Northern Ireland star nine strokes adrift of Van Pelt, who opened with three birdies, added another at 16 from nine feet then eagled from 45 feet at the par-5 17th and finished on 65.
Van Pelt, whose lone PGA title in 13 tour seasons came at Milwaukee in 2009, owned a one-stroke edge over a pack that included England's Paul Casey, Zimbabwe's Brendon de Jonge and Americans Cameron Tringale, Ben Martin, Hunter Mahan, Charles Howell, Brendon Todd and Jim Furyk.
McIlroy, whose win streak also includes his first World Golf Championships triumph, managed to reach only half the fairways.
"I just wasn't very good," McIlroy said. "It's very important here, if you are going to miss greens, miss it in the right spots, because I missed it in the wrong spot a couple of times and it's really tough to get it up-and-down."
McIlroy, who began on the back nine, found the rough at the 12th hole, then a greenside bunker and then missed the green when he blasted out on the way to a double bogey that he followed with bogeys at 13 and 18.
McIlroy birdied the fifth, took a bogey at eight and closed with a 32-foot birdie putt at the ninth.
"I think it's more to do with just not putting the adequate time into my game over the past week for obvious reasons," McIlroy said.
McIlroy denied that fatigue was a factor, despite a whirlwind week that has seen him in Florida and Northern Ireland as well as in New York to handle sponsor commitments and television appearances.
"It's I think just not putting the time in that I probably should have over the past week and I think I allowed myself that and deserved that," McIlroy said.
"But this is the sort of consequence of it and I need to work hard on it this afternoon and go out tomorrow and shoot a good number."
It was McIlroy's first time in his past 13 rounds he failed to finish under par.
"A score like this would be tougher to take if I had not just come off the weeks that I had," McIlroy said. "But at the same time, I want to play well and give myself chances to win tournaments.
"There are chances on this golf course to make birdies. I feel like I can do that."
US left-hander Phil Mickelson, who lost by a stroke to McIlroy at the PGA Championship two weeks ago at Valhalla, opened with a 71.
"The golf course is just in great shape but the rough is very thick, and I missed a few too many fairways, but had an OK start," Mickelson said. "Even par isn't what I wanted but it was still a nice day on the golf course."
Mickelson ranks 47th in season points and only the top 30 after the first three playoff events advance to the Tour Championship next month in Atlanta. Mickelson seeks his eighth trip in a row to the season's final event.
"If you play well, you can't worry about points, you can't worry about what other guys are doing," he said. "You just have to go out and shoot low scores and try to win the golf tournament. If you do that and get in contention, you're going to keep moving forward."
Leading scores on Thursday after the first round of the US PGA Barclays tournament (par-71, USA unless noted):
65 - Bo Van Pelt
66 - Cameron Tringale, Hunter Mahan, Charles Howell, Brendon de Jonge (ZIM), Ben Martin, Brendon Todd, Jim Furyk, Paul Casey (ENG)
67 - Ryo Ishikawa (JPN), Russell Knox (SCO), Danny Lee (NZL)
68 - Erik Compton, Steven Bowditch (AUS), Justin Hicks, Daniel Summerhays, Rickie Fowler, John Senden (AUS), Hideki Matsuyama (JPN), Bubba Watson, William McGirt, Kevin Chappell, KJ Choi (KOR), Jason Bohn, Noh Seung-Yul (KOR), Justin Rose (ENG), Zach Johnson, Matt Kuchar, Keegan Bradley, Ernie Els (RSA), Ricky Barnes