The diminutive Briton held a 60-mile advantage over countryman Mike Golding at 0300 GMT on Thursday but both competitors have not been without problems.

On Tuesday, the lashing that holds the gennaker halyard block to the top of the mast broke on Kingfisher, MacArthur's challenger.

And Golding then found himself competing without spinnakers after trouble throughout Wednesday and the early hours of Thursday.

The pair are both expected to finish late on Friday or early on Saturday.

MacArthur, though, insisted she was not content with her current advantage.

"For the moment everything is going well but yesterday I had a problem and had to drop the spinnaker in quite a lot of wind," she said on the Route du Rhum's official website.

"I'm really tired as I have spent a lot of time helming in the past two nights."

MacArthur said she felt like Golding was closing over the last 24 hours, despite her rival covering 327 miles to her 343 in that time.

"Yesterday I lost some miles with a sail change, it was stupid," she warned. "The stress is mounting but I'm trying to do things well so as to control it."

Race retirement

While MacArthur leads the monohulls, former rival Michel Desjoyeaux holds a massive lead in the multihulls.

Switzerland's Steve Ravussin had been leading until he capsized on Wednesday, making him the 15th boat to retire from the race.

He had been just 734 nautical miles from the finish.

"It's really sad and I am thinking about all those who have supported and helped me in this adventure," he said.

"When everything is reduced to nothingness you have to ask yourself if you would do the same thing tomorrow."