Francis Joyon, 51, set sail from Brest last Friday in an attempt to regain the record taken from him by MacArthur in February 2005.
Both Joyon and his compatriot Thomas Colville, who is yet to leave, are sailing longer boats than MacArthur's B&Q, which should ensure greater speed.
"I expect one of them to break it," said the 31-year-old Briton. "I don't know how I will feel about that. I just can't say until it happens."
MacArthur set the record of 71 days 14 hours.
Joyon, the 24-hour solo speed world record holder, should beat it in his 97ft trimaran IDEC II, which is 20 feet longer than the boat MacArthur used.
Colville, who had briefly to postpone his departure on Friday from Les Sables D'Ollones, has a 15ft advantage on MacArthur's B&Q in his boat, Sodebo.
The symbolic mark for the record is 70 days.
Mark Turner, MacArthur's long-time friend and business partner, hinted she would eager to reclaim the record should it be broken.
An attempt could take place after 2010, when her company's new multi-million pound sponsorship deal with BT expires. -- full article in BBC Sport:
news.bbc.co.uk/sport1/hi/other_sports/sailing/7112672.stm
* "I have to carry an alarm that warns me as soon as the boat crosses the 31 knots of boat speed mark," explained Francis Joyon this morning. "And all night, the alarm has been going off regularly in the *****pit!"
The first 24 hours for the IDEC skipper has been tough to say the least - 423 miles covered at 17.72 knots average and, with all the usual reservations, theoretically 82 miles ahead of Ellen MacArthur's record. At this pace it will not take long to pass Cape Finisterre...conditions remain excellent with the Azores high established and a depression over Morocco.
This provides a wide corridor of wind very well oriented for IDEC. "Now is the time to gain the maximum miles. The wind varies between 34 and 27 knots from the northeast, conditions very attractive to IDEC. The conditions ahead are very favorable, and we should continue to move quickly." -- TheDailySail.com
