Kevin Streelman of the United States and Denmark's Thomas Bjorn share the lead after the opening round of the World Cup at Royal Melbourne.
Streelman led the way for the Americans with a five-under-par 66 which featured five birdies on the back nine before two late bogeys checked his charge.
His team-mate Matt Kuchar could only manage a level-par 71 after four bogeys on the back nine.
Streelman said: "I made some good birdie putts today and some par saves as well, so pretty happy. It's just an incredible golf course, I love it. I just had a lot of fun there to be honest."
Bjorn also started strongly with a 66 as his team-mate Thorbjorn Olesen matched Kuchar's 71.
Bjorn had a poor start to his day, four-putting the fourth hole for a double-bogey six, but made a fine recovery.
He said: "I thought, 'Well, this could be a long day,' but I just kind of kept my composure and made some good birdies and kept playing solid. It is, in my eyes, probably the finest golf course you can ever play."
Portugal are in third place in the team event on two under - three behind both Denmark and defending champions USA - while in the individual standings third place is tied between South Korea's KJ Choi, Martin Laird of Scotland and Stuart Manley of Wales on four under.
Laird's compatriot Stephen Gallacher could only manage a 74, while English duo Danny Willett and Chris Wood opened with scores of 69 and 75 respectively.
Manley is playing as one of eight individuals in the 60-player field after Jamie Donaldson withdrew with a back injury.
In-form Australian Adam Scott, who has won the Australian PGA and Australian Masters over the past two weeks, had a quintuple-bogey nine on the 12th as he carded a 75.
Scott's compatriot Jason Day shot a solid 68 to be two off the pace, alone on three under.
Day, grieving the loss of eight relatives in the Philippines who were killed in Typhoon Haiyan, rolled in five birdies and two bogeys in his first round in five weeks.
Graeme McDowell, playing for Ireland, carded a one-over 72 with double-bogeys on the sixth and 18th wrecking his card although he holed a long-range chip for an eagle on the par-four ninth.
Watch the second round of the World Cup live on Sky Sport 4 HD from 3am on Friday