Palm Beach Gardens - Aussie Nathan Green and American Michael Connell shared the lead after one round of the Honda Classic, with unlikely Brazilian Alexandre Rocha hot on their heels.

Green and Connell defied difficult, windy conditions to card five-under 65s on the PGA National course.

Rocha, who made it through a pre-qualifier and a Monday qualifier and a playoff to get into the field, was in a group on 66 that also included Colombian Camilo Villegas and England's Oliver Wilson.

"I needed a day like today like, you have no idea," said Rocha, who is ranked 711th in the world.

The tournament is Rocha's fourth US tour event and his first since 2003. He lost his European Tour card last season, and is playing on the Asian Tour this year.

That move came only after he decided to continue his pro career - a decision he was inspired to make after golf was included in the programme for the 2016 Olympics in his homeland.

"I am surprised at how calm, how relaxed and how confident I felt all day," Rocha said. "That surprises me. I am not surprised about the fact that I can play proper golf. I've been working at it, and hard."

Of the two players who did better, Green notched five birdies in his bogey-free round.

He was especially pleased with the performance in a group with major title holders Vijay Singh and Padraig Harrington.

"You don't like embarrassing yourself in front of a crowd," Green said. "It can also help you, and I think that's sort of what it did today, playing with those guys.

"You definitely feed off them a little bit I think, just how calm they keep themselves."

Connell was a US tour rookie in 2006, when he made the cut in four of his 22 starts. He didn't make it back to the main tour until this season.

He jump-started his round with an eagle at the par-five third hole, and tied Green atop the leaderboard with a birdie at 17.

Fiji's Singh, Bubba Watson and DJ Trahan were all two shots off the pace on 67.

Singh, a former world number one, has seen his ranking plummet to 35 in the world. He believes a return to good health can fix that.

"I know I'm not supposed to be there," Singh said of his ranking. "The bottom line is, you play well, it's going to be OK. If you play well, the ranking is going to fix itself."

Defending champion Yang Yong-Eun of South Korea got off to a disastrous start, opening with a bogey at the 10th followed by a quintuple-bogey at 11 en route to a 79.

Leading first-round scores on Thursday in the $5.6 million Honda Classic (USA unless noted):

65 - Michael Connell, Nathan Green (AUS)

66 - Alexandre Rocha (BRA), Camilo Villegas (COL), Oliver Wilson (GBR)

67 - Vijay Singh (FIJ), D.J. Trahan, Bubba Watson

68 - Henrik Bjornstad (NOR), Jonathan Byrd, Alex Cejka (GER), Tom Gillis, Anthony Kim, Graeme McDowell (NIR), George McNeill, Scott Piercy, Alex Prugh, Ted Purdy

Notable others:

69 - Angel Cabrera (ARG), Fredrik Jacobson (SWE), Richard S. Johnson (SWE), Matt Jones (AUS), Lee Westwood (GBR)

70 - Aron Price (AUS), Justin Rose (GBR), Brendon de Jonge (ZIM)

71 - Padraig Harrington (IRL), Rory McIlroy (NIR), Jeev Milkha Singh (IND), Mike Weir (CAN)

72 - James Nitties (AUS), Greg Owen (GBR), Charlie Wi (KOR)

73 - Stephen Ames (CAN), Paul Casey (GBR), Tim Clark (RSA), Ernie Els (RSA), Trevor Immelman (RSA), David Lutterus (AUS)

74 - Stuart Appleby (AUS), Graham Delaet (CAN), Sergio Garcia (ESP), Marc Leishman (AUS), Nick O'Hern (AUS), John Senden (AUS)

75 - Brian Davis (GBR), Andres Romero (ARG), Tim Wilkinson (NZL)

76 - Robert Allenby (AUS), Greg Chalmers (AUS)

77 - Mathias Gronberg (SWE), Carl Pettersson (SWE)

78 - Mathew Goggin (AUS)

79 - Yang Yong-Eun (KOR)