Emirates Team New Zealand continue to lead the Louis Vuitton America's Cup World Series lead in Chicago today.

Going into the event, New Zealand held an eight point lead over Oracle Team USA and the Kiwis leave Chicago with a 10 point advantage over Land Rover BAR, who is tied with Oracle.

Emirates Team New Zealand continues to lead the Louis Vuitton America's Cup World Series. Photo: Supplied.

The regatta was perhaps Emirates Team New Zealand's toughest regatta yet, finishing in fourth place- the first event the team has finished off the podium.

The latest round has been a tough regatta testing the entire fleet.

'It was really tough out there,” says skipper Glenn Ashby. 'The wind was up and you look along the start line and there are no easy beats.

'We have been saying it all along, and the results of this regatta show just how good all of the teams are. We finished fourth, you are never satisfied with that, but if there is any consolation we managed to beat Oracle again, and increase our lead overall so that's good.”

The full schedule of three races was sailed this morning (NZ time) meaning New Zealand's win in yesterday's substitute race counted for nothing, says Emirates Team New Zealand in a media statement.

Glenn says the wind swung around over night to the north blowing down Lake Michigan as blustery 12-14 knots and gusting up to 20 knots at times. Perfect conditions for high action in front for the large Navy Pier crowd.

He says the lead up to the regatta starting well was going to be the key to success on the tight enclosed race course. Something he says the team didn't quite manage to nail.

Tauranga sailor and helmsman for Team New Zealand Peter Burling says the racing is super tight and the team had a tough day.

'A few things didn't quite swing our way which we were hoping would.”

The boat rounding the first mark in front extended their lead throughout in each of the three races, while the rest of the fleet battled it out for vital positions in each and every race.

'We have done such a small amount of training in these boats, it is super hard to put together a consistent performance in such tight racing,” says Peter.

'We have a lot to work on but we are really happy to extend our overall lead and beat the guys we are fighting against, especially Oracle Team USA.”

The next Louis Vuitton America's Cup World Series event is in Portsmouth, UK on July 23 and 24.