A horror hole has severely jeopardised Adam Scott's winning streak but fellow Australian Jason Day is within two shots of the World Cup lead.
Denmark's Thomas Bjorn and American Kevin Streelman lead the tournament at Royal Melbourne after each shot five-under-par opening rounds of 66 on Thursday.
Their nations also lead the team event, after their respective partners, Dane Thorbjorn Olesen and American Matt Kuchar, each shot even par to make team totals of five under.
World No.2 Scott, coming off wins in the Australian PGA and Masters, shot a four-over 75, including a quintuple-bogey when he used three balls off the tee on the par 4 12th.
Day, dealing with the grief of losing eight relatives in Typhoon Haiyan, shot 68 despite dealing with tougher, windier conditions playing in the second-last group.
The pair's one-over total leaves them six shots adrift as they try to win the World Cup for Australia.
Day said he wouldn't speak with Scott before Friday's second round, as he sensed his teammate wouldn't be in the mood.
"He looks tired, he looks exhausted after the last two weeks," he said.
Day was delighted with his own game, coming off a five-week break in which his practice has consisted of hitting balls into a net in his garage or chipping them into his young son's toy collection in their basement.
US Masters champion Scott admitted his mind wandered on the 12th.
His initial tee shot went way right and he lost the ball.
His second went deep into a grove of trees and he was unable to play that either.
His third attempt off the tee counted as his fifth shot and he needed four more to complete the horror hole.
"I was just away with the fairies on that hole," Scott said.
He said mental fatigue might have kicked in and a lapse in his game had been inevitable at some point.
"You just can't play good all the time," Scott said.
But he still holds hope of a comeback victory, saying with Royal Melbourne's greens fast and getting faster it might not take spectacular scoring to rein in the leaders.
"If I can plug away at it I'll maybe claw my way back into it," Scott said.
