The two time defending champions on The Wave finished the day at the top of the leaderboard with their Swiss rivals in third place, five points behind. But to retain the title, McMillan needs to win the Sydney event and hold Alinghi off to sixth place or lower by the close of racing on Sunday.

After the first day of racing on Thursday was cancelled due to high winds, conditions had eased slightly with around 18 knots of breeze and gusts that gathered strength as the day progressed proving challenging for the entire fleet. Racing on the tight course in Sydney Harbour in front of the Sydney Opera House was tricky but after a slow start, the experience on The Wave, Muscat started to pay dividends as the team got into their stride to earn five podium places in the last six races, including two outright wins.

“It was a good day but we still have a lot to do,” said McMillan, racing with his top-notch crew of Sarah Ayton, Pete Greenhalgh, Nasser Al Mashari and Ed Smyth.

“These conditions were difficult – it was touch and go at times and things started to get patchy towards the end but we mixed it up a bit and finished up where we wanted to be. If we can keep going with how we were sailing in the second half of today, we might just do it.

“Everyone sailed really well and our communications on board were good so let’s hope we can take all that into tomorrow. Whatever happens, it is great to be racing in Sydney Harbour.”

The crowds lining the shore, enjoying the action on the rocks just metres from the race course, gave local boy Slingsby, who grew up in Gosport on the New South Wales coast, a rousing welcome on his debut as helm on Oman Air though until the final race, he admitted he found his first time on an Extreme 40 to be a major test.

“It was always going to be tough because there was no chance to practice so I never expected to be at the front. A couple of jury decisions baffled me so I’m trying to figure all that out but in the final race, we had a good start and kept our noses clean. We stayed out of trouble and sailed well and it was great to win a race for Oman Air.

“I do not want to be at the bottom of the leaderboard tomorrow. We will get better for sure so our aim is to just keep ticking away and move up the leaderboard so we can finish in a respectable position.”

Conditions in Sydney Harbour are expected to be lighter tomorrow when the second day of racing starts at 1430 local time (GMT +11). Online fans can follow it live on the official event website with television and text commentary at www.extremesailingseries.com.