The supermaxi, which has only been beaten to Tasmania twice in eight previous versions of the race, overhauled local rival Perpetual Loyal early in the afternoon on day two.
Perpetual Loyal skipper Anthony Bell bemoaned the light winds but did not rule out snatching the lead back from Wild Oats as they did in stormy weather late on Thursday night.
"The pressure may actually be back on the leading boat, particularly as they try and navigate their way in the final (part) of the race," said Bell, who skippered Investec Loyal to victory over Wild Oats in 2011.
"So as long we stay in touch and try and stay somewhere in strike, yeah, we're definitely still trying to win this race."
Wild Oats, trying to equal the seven line honours victories of the boat called Morna and later renamed Kurrewa IV, is expected to sail up the Derwent River to the finish of the 628 nautical-mile (1,163km) race late on Saturday afternoon.
The remainder of the 92-boat fleet -- two yachts withdrew for technical reasons on day one - is forecast to face winds of 40-60 knots and waves of up to 12 metres on Sunday as they enter the notoriously volatile Bass Strait.
A repeat of the major storm that sank five yachts and killed six sailors in 1998 is unlikely, however.
The international competition has been boosted by 12 boats from the Clipper Round the World Race, which for the first time is including the race as part of its 40,000 nautical mile, 11-month race.
Wild Oats XI holds the race record of one day, 18 hours, 23 minutes and 12 seconds set last year, but the light winds means it will not come close to that time this year.