( CNN ) -- Denmark 's Thomas Bjorn and American Kevin Streelman are tied for the lead after Thursday 's opening round of the World Cup of Golf in Melbourne . Both men fired rounds of 66 to finish on five-under par at the Royal Melbourne Golf Club to take their respective nations to the top of the team standings . Historically , the tournament has been primarily a team event , but format changes this year have made it `` an individual event with a team component , '' say organizers . Gallery : World 's greatest island greens . Individual players are competing in 72 holes of stroke play and vying for $ 7 million of the $ 8 million prize pot . The remaining $ 1 million will be shared between the leading teams . Bjorn 's Danish teammate Thorbjorn Olesen and Streelman 's partner Matt Kuchar ( who won the team event with Gary Woodland in 2011 ) both shot level par rounds of 71 . Portugal are currently lying second on two-under par thanks to rounds of 69 from Ricardo Santos and 71 from Jose-Filipe Lima . `` I played well today , '' BjÃ¶rn told reporters . `` I got off to a bit of a not so great start when I four-putted number four and then I thought , 'well , this could be a long day ' , but I kept my composure and made some good birdies . I did everything well today . I drove it pretty well . '' Streelman was equally content despite dropping two shots in the closing three holes . `` I was very pleased with that start . It 's just an incredible golf course , I love it ... I just had a lot of fun there to be honest , '' Streelman said . He and Bjorn are one shot ahead of South Korea 's K.J . Choi , Welshman Stuart Manley and Scot Martin Laird . Home favorite Jason Day shot a highly respectable 68 to take sixth place on his own . The 26-year-old , who is mourning the loss of eight relatives in the Philippines following Typhoon Haiyan , finished three-under par after claiming five birdies and two bogeys . Read more : Jason Day loses eight relatives . There were mixed fortunes for some of the bigger names on show at the famous old course . Masters champion Adam Scott , who won the Australian Masters at the same course last week , carded a four-over par 75 which included a quintuple-bogey nine at the par four 12th hole . Northern Ireland 's Graeme McDowell had a day of wildly fluctuating fortunes . The former U.S. Open champion only had two pars on the opening nine which included three bogeys , a double bogey , three birdies and an eagle two at the par four ninth hole . His erratic form continued on the back nine and he eventually closed out with a double bogey to card a one-over par 72 .
Australian and U.S. teams lead World Cup of Golf at Royal Melbourne after rounds of 66 . World Cup format changes in 2013 becoming an individual event with team component . Home favorite Adam Scott shoots a quintuple nine at par for par in round of 75 .