Sweden's Alex Noren and American Webb Simpson shot four-under-par 66s for the lead as Tiger Woods and Graeme McDowell were at even par for the opening round of Florida's Honda Classic.
McDowell heads a considerable Irish challenge on level par thanks to a mixed round which saw him hit back-to-back bogeys on the second and third holes before erasing them with two birdies just before the turn.
The Antrim man repeated that feat on the back nine, finishing with two birdies to cancel out bogeys on the 11th and 16th holes.
McDowell recorded the longest putt of the day at 63ft 9in on the par three 17th, one of only nine birdies on the hole.
Shane Lowry had a similarly mixed round with three birdies and four bogeys to leave him a shot further back from McDowell on +1, while Rory McIlroy signed for a 72 to leave him on +2.
McIlroy negotiated 'The Bear Trap' but stumbled on Palm Beach Gardens' punishing 18th to finish the opening round of the Honda Classic six shots off the pace.
Completing the first round level with reigning Masters champion Sergio Garcia on two over, McIlroy had looked to be in good shape as he carded two birdies on the third and fourth.
However, blustery conditions accompanied bogies on the sixth and seventh and the former world number one failed to break par for 10 holes straight.
McIlroy cleared the challenging 15th, 16th and 17th holes - dubbed The Bear Trap - on par, but fell victim to the 556-yard 18th to card a double bogey.
The 2012 champion told the PGA website: "It was a pretty tough day. (The) wind was up, (the) greens got a little sort of crusty and firm.
"I felt like I was hanging on pretty well, doing what I needed to do, just sort of grinding out pars and was pushing for a birdie at the last to try and shoot under par and just tried to hold a three wood into the wind and overdid it a little bit.
"So, a disappointing finish but we'll get back out tomorrow morning and try to rectify that mistake and start again."
Padraig Harrington and Seamus Power appear to already have a battle to make the cut on their hands as they hit rounds of 76 and 77 to leave them on +6 and +7 respectively.
After failing to make the cut in the Genesis Open last week, Woods played the best round of his comeback, hitting 10 of 18 greens and seven of 14 fairways.
The former world number one said he was pleased with his round of 70, which left him in a tie for 21st.
"Today was not easy" said the 14-time major champion, who is making his third start of the PGA Tour season after a long absence following back surgery.
"It was tough all around today. One, the wind was blowing pretty hard. Then it was tough to make putts out there."
Yet Woods said he was happy with his putting on bouncy greens. "I made a lot of key short putts for par," he said of his first back-to-back weeks of playing in three years.
Defending champion Rickie Fowler finished one over par to sit in a 20-way tie for 36th. Only 20 players out of a field of 140 completed scores under par in the opening round.