Olympic legend Ben Ainslie says there are up to a dozen sailors with a realistic chance of denying him a fourth gold medal in London.

The Macclesfield-born Finn racer has had a mixed 2012 but will take to the Weymouth waters as favourite to add to a mighty haul of gold and cement his position as the greatest olympic sailor ever.

And, with younger and stronger competitors pitching up against him, the 35-year-old says there isn’t a single rival he should fear – it’s more like a dozen.

"The reality is that it’s very tight," he said. "There’s a really good group of sailors there and any one of 10 or 12 sailors on their day are capable of going out and winning races and being tough to beat.

"There’s not one guy in particular who stands out as being a main rival, it’s more that there’s a group of guys."

Ainslie first competed in the Olympics at the 1996 Games in Atlanta, where he was forced into silver medal position by Brazilian Robert Scheidt.

However, after Ainslie pipped Scheidt to top spot in Sydney four years later, he would dominate the class, with further gold in Athens and Beijing.

In the past 12 months he’s suffered with a back injury that required surgery and, in the world championships in Perth last December, boarding a media boat to remonstrate with its occupants saw him disqualified from two races.

And, at the last outing in Weymouth in June, Ainslie took an embarassing dip as he challenged fellow Brit Giles Scott on the water.

But he remains the man to beat and with his historic bid now a matter of days away he insists: "You have to keep on improving, the game is always moving on. You’ve got to try to stay at the top of that."

The first Finn race will be held on Sunday, July 29.