An astounded Tiger Woods exceeded his own expectations in his first tournament for almost five months as veteran Fred Couples charged into a one-shot lead in the US Masters first round on Thursday.

Disgraced world number one Woods, welcomed back from self-imposed exile by cheering crowds at Augusta National, soared into contention with two eagles on the way to a four-under-par 68 to lie two strokes off the pace.

"It's unbelievable," Woods told reporters after breaking 70 for the first time in the opening round at Augusta in his 16th Masters appearance.

"I would think that a couple under par would have been probably a pretty good start," he added.

While the world number one had to be feeling a little anxious, he offered a warm smile as he shook hands with playing partners Choi and American Matt Kuchar on the first tee.

The official starter announced: "On the tee, Tiger Woods," prompting loud cheering by fans crammed on either side of the fairway in front of the imposing clubhouse at Augusta.

There were calls of "Go Tiger" and "We love you Tiger," not a hint of heckling and plenty of hooting and hollering in the loudest applause the world number one has received all week.

"It was unbelievable all day. I haven't heard them cheer this loud in all my years here," he said.

"Everybody seemed to go low today and there are 30-plus guys under par. So the golf course, even though it was windy, it could be had today. If I putted well today, it could have been a really special round," he added.

While the 14-times major winner drew the day's biggest gallery, 1992 champion Fred Couples fired a sizzling 66 in breezy conditions to take command of the year's opening major.

Maintaining the loose-limbed form that has swept him to victories in his last three starts on the seniors tour, the 50-year-old American birdied four of the last seven holes to break clear of the field.

On a gripping day featuring sudden weather changes and electric displays by several former champions, 60-year-old Tom Watson defied his age to share second place on 67 with fellow American Phil Mickelson, Britain's Lee Westwood and South Koreans Yang Yong-eun and KJ Choi.

American Anthony Kim birdied the last three holes for a 68, finishing level with compatriots Woods, Nick Watney and Ricky Barnes, and British world number seven Ian Poulter.

While Woods began his opening round in strengthening winds, eight-times major winner Tom Watson was putting the finishing touches to a vintage display.

Watson, who came agonisingly close to the most remarkable major victory of all time before losing the 2009 British Open at Turnberry in a playoff, rolled in a five-footer to birdie the last before throwing his arm skywards.

"I did what I had to do today and took advantage of some of the holes that you could take advantage of," Watson said.