Veteran British yachtsman Sir Robin Knox-Johnston has been forced to return to port after rolling his vessel 360 degrees during the Velux 5 Oceans race.
Knox-Johnston's is the fourth boat to return to harbour
Knox-Johnston, on board Saga Insurance, had the incident in "boat-breaking" gale conditions off the coast of Spain.
"Rolled last night. Section of mast track bent. Can't remove all the screws so sail stuck," he said via e-mail.
The horrendous weather had already forced three boats to return to harbour just 24 hours into the contest.
The race began from Bilbao, Spain, on Sunday with eight skippers but Britons Mike Golding and Alex Thomson and Spain's Unai Basurko returned to Gijon in the north of the country after 60-knot winds caused havoc in the Bay of Biscay.
And now Knox-Johnston is sailing towards La Coruna for repairs to his mast track and communications systems.
Golding, from Southampton, Hampshire, who is onboard Ecover, said the sea was "enormous", and "the main thing is just to get through this and not break anything".
He added: "There is not much I can do. I was caught out a bit and could not really get prepared for this."
Thomson, from Gosport, Hampshire, aboard Hugo Boss, returned after experiencing gear failure.
"I am obviously disappointed but I have no other option than to suspend racing in order to carry out the necessary repair and continue in the Velux 5 Oceans," he said.
"I am just glad this happened early on in the race before I was too far offshore."
In 1969 Knox-Johnston became the first person to sail non-stop around the world alone, and at 67 he is the oldest participant in the Velux 5 Oceans.
He was 30 when he took 312 days to circumnavigate the world in his 32ft wooden yacht Suhaili in the Sunday Times Golden Globe race. He was the only competitor to finish.
"I didn't enter this race just to participate," he has previously said.
"People often think that life winds down for the over 50s, but this simply isn't true."
Knox-Johnston is returning to racing after a self-imposed retirement since his wife died from cancer.
He last raced in 1994 when, with the late Sir Peter Blake, he broke the round-the-world sailing record and won the Jules Verne Trophy.
The three-leg race includes stops in Fremantle, Australia, and Norfolk, USA.
The first leg of the race, which is widely considered to be the world's toughest solo round-the-world yacht race, started from Bilbao, Spain, bound for Fremantle, Western Australia.
The leg is expected to take about six weeks.
This year marks the 25th anniversary of this solo round-the-world race, know previously as the BOC Challenge and Around Alone.