Barclays Classic: Ryder Cup hopeful Paul Casey was delighted to have made an unusually strong start to The Barclays but Pádraig Harrington struggled to keep with the blistering pace set by Hunter Mahan at Ridgewood Country Club.

Casey, hoping to prove his worth for a captain's pick from Nick Faldo ahead of decision day on August 31st, shot a five-under par 66 in a round containing eight birdies and three bogeys on the par-71, 7,319-yard championship lay-out in this first of four FedEx Cup play-off events.

The Englishman was pleased with his round but it still left him four shots behind clubhouse leader Mahan, who fired an opening 62: "I'm very happy with that. I've struggled to get off to a good start this year," said Casey.

"First rounds have been not so good, so that was great."

Casey was quickly in the groove at Ridgewood, making three birdies in his opening four holes. He sent his approach shot from 98 yards at the par-four first to within three feet of the hole from where he birdied.

At the par-three second he holed out for another birdie from 24 feet and after scoring par at the third he sent down a 21-foot putt to birdie the par-four fourth.

Casey wobbled with bogeys at the sixth and seventh to reach the turn in 34 but bounced back at the 11th after finding the rough with his tee shot at the 467-yard par four.

The recovery shot from 204 yards out came to rest less than two feet from the hole and he putted for birdie, doing likewise at the 12th.

A bogey five at the 14th was quickly remedied with birdies at 15 and 16 and Casey finished in style with a 15-foot putt for birdie at the 18th to go into the clubhouse at five under.

He explained: "The greens were perfect this morning. 7.21am was a lovely tee time, and I was just happy to take advantage of that.

"Especially that putt on 18, because I felt like I let one go on 17, so that was a nice way to finish it."

Harrington, with three majors under his belt and fourth in the standings, returned to action 11 days after his US PGA Championship victory at Oakland Hills, opened his round at the par-three 10th with a tee shot to four feet from the hole to get his day up and running with a birdie.

The Dubliner, playing with Kenny Perry and Phil Mickelson in a group of the top-ranked FedEx Cup players, came unstuck at the turn, however, double bogeying the par-four 18th. Harrington then birdied his 10th hole but bogeyed the par-five third on his way to an opening 72, one over par.

Perry, number two in the FedEx points standings, bogeyed his last for a two-under 68 with Mickelson, ranked third behind Perry and the absent Tiger Woods, carding a one-under 69.

Mahan, bidding for one of US captain Paul Azinger's four picks for the clash with Europe at Valhalla next month, was even more impressive.

He opened with an eagle at the first, holing out from 99 yards and followed with eight birdies and one bogey for a nine-under-par-round of 62, the fifth time in his career he has scored that number.

"It feels good," Mahan said. "It's a tough golf course.

"I thought if you shoot in the red all week, in the 60s all week you'll have something at the end there. I feel great and love this golf course and I'm excited about the next couple of days."

Casey was a stroke ahead of a four-way tie on four under between Americans Charley Hoffman, Bo Van Pelt and Kevin Streelman and Australia's Matt Goggin - with Ryan Palmer on the same score after six holes and Dudley Hart after 12.

Among a group another shot back with first-round 68s were Adam Scott, Rich Beem and Swedish veteran Jesper Parnevik while Anthony Kim, a two-time winner in the US this year and fifth on the FedEx Cup points standings, was going well at three under through nine holes.

Ian Poulter's bid for a place on the European Ryder Cup team via the world points list hit a snag with the Englishman posting three bogeys and one birdie for a two-over-par round of 73.

Poulter needs a sole fourth-place finish at Ridgewood on Sunday with Justin Rose placing outside the top two at the KLM Open in Holland if he is to move onto the top five automatic qualifying places on the list.