After several planned practice races were abandoned due to a lack of wind, Barker managed to get a victory over his old team - their first loss of warm-up racing.
Beforehand Team NZ edged Luna Rossa in what was a mixed day for the defender, but Barker outfoxed the Kiwis in the windshifts in the last race of the day to claim a morale-boosting win for the American squad.
Also having a mixed outing was INEOS Team UK, with the struggles of the British syndicate having been an underlying theme of the warm-up period, with the team not completing a trial race until Tuesday, when they finally faced off against Barker's American Magic.
Ben Ainslie's team took no part last week and pulled out halfway through the pre-start on Monday against Team New Zealand, due to unspecified hardware problems.
They finally managed to complete a trial race and also won the start against American Magic, with Ainslie timing his run to the line perfectly.
Enjoy smooth sailing to the Cup with Auckland Transport
• Avoid traffic congestion and parking niggles and download the AT Mobile app to plot your bus, train or ferry ride to race venues before you leave home.
• Make sure your AT HOP card is in your pocket. It's the best way to ride to the Cup
• For more ways to enjoy race day, visit at.govt.nz/americascup
