The race favourite led the 82-strong fleet out to sea from Sydney Harbour, although forecasters say “soft” winds mean the Australian yacht is unlikely to beat its record of 18 hours, 40 minutes and 10 seconds set in 2005.
Rival supermaxis Leopard and Skandia followed Wild Oats out of the harbour, intent on chasing down the title-holder during the 628-nautical mile race down Australia's east coast to Hobart on the island state of Tasmania.
Light winds prevented the yachts unfurling their colourful spinnakers for the opening run out of Sydney Harbour, with the calm conditions also preventing the collisions and rule infringements that have marred previous starts in the congested waterway.
The three supermaxis, the largest yachts in the race at 30 metres (98 feet) are expected to dominate the race, with Wild Oats the bookies' favourite, followed by Britain's Leopard and fellow Australian Skandia.
The 2005 and 2006 winner, is bidding to become the first yacht since 1948 to win line honours three years in a row.
It was leading at 5:00pm (AEDT), four hours into the race, followed by 2003 winner Skandia and Leopard.
Sydney yacht Zephyr was leading the race for handicap honours, followed by Skandia and US yacht Rosebud.
Forecasters expect perfect racing conditions in the first 24 hours but winds are likely to ease Thursday, meaning the race record is unlikely to be threatened.
“That's why records are called records; they are elusive things and very hard things to beat,” Wild Oats skipper Mark Richards said.
“Thursday could be a very slow day and for the record you can't afford to have too much time going slowly. We could even park up for four or five hours so that really hurts.
“It's going to be a very tricky race out there and we'll have to work very hard tactically. Anything could happen. It's still a couple of days out but it's looking trickier every day.”