World sailor of the year Iker Martinez made the worst mistake of his career to gift the Itajai in-port race to French boat Groupama and keep the Volvo Ocean Race wide open on Saturday.
Martinez, an Olympic champion for Spain in Athens in 2004 and a silver medallist four years later, looked to be heading for his third in-port race win in the series to stretch Telefonica's overall lead but sailed around the wrong turning buoy mid-way.
As his Telefonica boat sailed hundreds of metres off course, Groupama and the rest of the fleet sped past the hapless Spanish crew who ended a distant last.
Camper (Spain/New Zealand) were second, 48 seconds behind, with Puma third despite an early timing penalty for cutting across a rival boat.
The result cuts Martinez's lead at the head of the standings to 16 points -- a slim advantage as each of the remaining four legs is worth 30 points apiece to the winners.
Franck Cammas' fast-improving French crew lead the chasing pack.
The 34-year-old Martinez did not try to dodge blame for Saturday's calamitous mistake.
"We had sailed a nearly perfect race until then," he said. "There were two marks and I chose the wrong one.
"It's the first time in my life I've ever made a mistake like that so I feel terrible for the shore crew who had worked so hard."
Cammas added: "We were very close to making the same mistake but (helmsman) Charles Caudrelier made a good call and we were lucky."
The fleet next heads to Miami starting on Sunday.
All but leg victors Puma suffered damage in the treacherous leg five from Auckland to southern Brazil and China's Team Sanya (broken rudder) will not rejoin the race until it arrives in Florida next month.
The 39,000-nautical mile, eight-month marathon -- offshore sailing's longest and toughest professional race -- is scheduled to finish in Galway, Ireland in early July.
Overall standings: 1. Team Telefonica (Spain) 149 points, 2. Groupama (France) 133, 3. Camper (NZ/Spain) 124, 4. Puma (U.S.) 117, 5. Abu Dhabi 58, 6. Team Sanya (China) 25