Rory McIlroy opens with six-under-par 66 at Players Championship

Rory McIlroy posted an impressive first round of six-under-par 66 to move into early contention at the Players Championship at Sawgrass in Florida.

McIlroy recorded six birdies in a bogey-free round to lay down a marker to the assembled high-quality field.

American Roberto Castro is the clubhouse leader on nine under, with McIlroy and Zach Johnson three behind.

Graeme McDowell carded five birdies and three bogeys to lie two under while Padraig Harrington is four under.

Having failed to make the cut or even broken par in his three previous appearances at the tournament, McIlroy registered five birdies in his first eight holes after starting from the 10th.

McIlroy's scoring average of 74 in golf's 'unofficial fifth major' looked set to tumble after the world number two went to the turn in 31.

Video caption, Rory McIlroy adopts a new, more conservative strategy at the Players Championship at Sawgrass.

The 24-year-old from Northern Ireland birdied the par-five 11th, 12th and 14th to stand three under par approaching the daunting closing stretch.

A pushed drive on the par-five 16th meant McIlroy was unable to reach the green in two, but after pitching to 20 feet he rolled in the birdie putt and then struck a superb tee-shot to the island green on the famous par-three 17th.

The two-time major winner - without a win so far in 2013 after five victories around the world last year - converted the birdie putt from seven feet and added a par on the 18th to remain five under par.

The Holywood man missed from 12ft for another birdie on the first, but picked up a shot on the par-five second after coming up short of the green and then hitting an excellent pitch to two feet.

Another birdie opportunity went begging on the fourth but McIlroy was still happy with his start.

"I'm adopting a more conservative strategy off the tee this week and I think it's going to help me," said the reigning USPGA champion.

"If you hit the ball onto the fairway more often on this course, then are going to have chances to get close to the pins.

"That is something I did today and I need to keep doing it over the next three days.

"My game has progressed nicely in recent weeks and I've been shooting scores that are really promising. Some of the signs I've been seeing on the golf course are very promising."