If Telefonica are found guilty of the breach, possible penalties include being relegated a place for the leg, which would see Team New Zealand's entry Camper elevated to third for the Auckland leg, and reclaim second place in the overall standings from Groupama.
It would also mean Telefonica's buffer at the top of the leaderboard would be reduced to just eight points.
Prior to leaving Sanya, Telefonica were well in control of the race with an 18 point lead over Camper after winning the first three legs of the race.
Their third place finish in to Auckland left the door narrowly ajar for their closest rivals, but if Telefonica are docked further points by the jury, that door will be thrown wide open.
Late last night the Spanish team were in fifth place in the race to Itajai, after an action-packed fourth day of racing in which the lead changed three times.
Telefonica were 55 nautical miles behind Team Sanya, skippered by Kiwi Mike Sanderson, who took a surprise lead after finding the wind further south of the rest of the fleet.
Groupama were in second place 10 miles behind Sanya, who are sailing in a boat recycled from the 2005/06 edition of the race, with Camper in third a further four miles back.