Team Malizia and 11th Hour Racing Team remain locked in a battle that appears destined to last until the finish line off Newport, Rhode Island is in sight. 

On Friday morning (UTC), first Malizia and then 11th Hour Racing Team put in successful gybes as the wind shifted south. 

The transition immediately showed as a benefit for Charlie Enright's team who made at least a theoretical gain on the tracker from being on the inside lane.

But Will Harris and his Malizians retain a modest lead of just under 10 miles, as the two boats now streak towards the southeast coast of the United States.

Ahead of them is more uncertainty: the wind will shift again, this time in front of them, pushing them back off the coast; they will begin to encounter the Gulf Stream current which pushes to the northeast; and final 48 hours of the leg promises to be "complicated with many transitions, which are still unclear," according to race meteorologist Christian Dumard. 

The ETA remains May 10th for the leading pair. But how they get there is far from certain.

Behind, the team that has suffered most over the past hours is Paul Meilhat's Biotherm, who began to weave to the left on the tracker, and slow down significantly, around 05:20 UTC on Friday morning. The slowdown to speeds averaging just 4 knots would last for hours, prompting speculation there was a problem on board. 

As it turns out, the team had sailed into a big windless area that didn't appear on any weather forecasting or satellite models. 

"We're just surrounded by a glassy sea," was the description off the boat.

"People are sending messages to ask if we've broken anything, but the only thing wrong is the wind," said Mariana Lobato.

The team is doing better again as of the 14:00 report, but the big slowdown has presented an opportunity to Guyot environnement - Team Europe. After trailing a podium spot by nearly 200 miles earlier this morning, the team is now (1400 UTC) just 60 miles in arrears, a remarkable turn of events. 

With the uncertain conditions ahead, there is more of a chance for the Guyot crew to get back into the podium race than ever before.