AUGUSTA, United States (AFP) - Tiger Woods was struggling to kick-start his career at the Masters on Thursday, while Rory McIlroy made a quiet start to his bid for a slice of golfing history.

While the two big names of the day strived to find their best form at Augusta National, others stepped up to set the pace on a day when perfect playing conditions opened the door to sub-par scores.

England's 2013 US Open champion Justin Rose and US journeyman Charley Hoffman were the clubhouse leaders by mid-afternoon with both carding five-under 67s.

One shot back on 68 was Russell Henley, with back-to-form Englishman Paul Casey, former US Open champion Webb Simpson and Bill Haas all in on 69.

Still out on the course, highly fancied Jordan Spieth was at four under, the same as 45-year-old Ernie Els, many times a Masters' contender.

Tom Watson, meanwhile, at 65 became the oldest player ever to shoot under par at Augusta National with a 71.

Woods returned to Augusta National, the scene of some of his greatest triumphs, ending a two-month, self-imposed timeout during which he tried to put his fractured game back together again.

The 39-year-old American was given a warm reception when he strode onto the first tee, having wooed the Masters fans all week with his new, friendlier, more open demeanor.

Having turned it on in practice and in the par-3 contest, he immediately found it tougher going out on the course for real.

An opening three-putt for bogey was matched with a birdie at the par-five second, but his strugglng short game was letting him down again and he dropped another at the fourth when failing to get up and down from a bunker.

Woods still needs four more major titles to match the all-time record of 18 set by Jack Nicklaus in 1986. That quest has been the driving force of his career.

Woods' dramatic return to the fray was just one storyline in one of the most hotly-anticipated Masters in years.

By the time he smacked his opening drive, world No.1 McIlroy had already posted a solid start to his seventh, and to date most significant, Masters campaign.

At 25, McIlroy would be the second-youngest player ever to complete the full set of Grand Slam titles were he to emerge truimphant on Sunday.

Only Woods, the last of five players to have achieved that feat, in his case nearly 15 years ago, was younger at the time.

Like Woods, McIlroy was handed a rousing reception as he stepped onto a packed first tee to take his place in a grouping that also included three-time former winner Phil Mickelson and Ryan Moore.

McIlroy opened with five straight pars before taking his first bogey at the par-three sixth. But he birdied the next to reach the turn at level par.

A second dropped shot at the 11th, when he missed a 12-footer, had him shaking his head though, but he birdied the two par-fives on the back nine to come in with a workman-like 71.

BUBBA STARTS ON 71

Ahead of him, defending champion Bubba Watson was aiming to become just the second player, after Jack Nicklaus, to win the Masters three times in four years.

The big lefty briefly was joint pace-setter with two early birdies. But he promptly dropped one and thereafter trundled along in uncustomary conservative fashion at two under until dropping another one at the last for a 71, the same as namesake Tom.

Rose, who has been struggling all season after a wrist injury, suddenly rediscovered the form that made him a major winner with a round that contained six birdies and one bogey.

It equalled his best-ever start to a Masters, which he set in 2004 and which he put down to the hard work he has put in on the range recently.

"I had to iron out a few kinks. I wasn't that happy with where my swing was at about a month ago. Chopping and changing putters a couple times through the Florida Swing," he said.

Australian 2012 Masters champion Adam Scott bogeyed the last for a level par 72.