The United States took a 7-5 lead over the UK and Ireland on the last Sunday of the 48th Walker Cup after an intriguing opening day at the Seminole Golf Club in Florida.
The morning fours ended 2-2, with Irish pair Mark Mark and John Murphy picking up GB & I’s first point after a sensational brawl.
Angus Flanagan and Jake Bolton scored the second point in another close match.
Power, Matty Lamb and Barclay Brown recorded individual victories in the afternoon.
GB&I is hugely behind the two-year competition of amateur teams. They have won only twice on American soil in an event that first competed in 1922, and all 10 Americans are ranked among the top 30 amateurs in the world, while visitors have only two.
The players of both teams were affected by “gastrointestinal problems” before the competition, but Covid was quickly ruled out given all the tests that took place.
All four matches in the morning four went to the 18th hole.
Power and Murphy had three wins after 12, but won the next three holes to tie their match with Quade Cummins and Austin Eckroat.
They then beat a pair-three 17th for the lead for the first time in the match and halved the last to win a point.
Flanagan and Bolton were two by four, but lost 15th and 16th holes. However, Bolton traveled a stunning pair to win the 17th and they halved the last.
In the first match, Alex Fitzpatrick and Barclay Brown won three consecutive 14-hole to equalize their match with Cole Hammer and Davis Thompson, but Hammer carved a 20-foot birdie in the final to win the 1UP.
Jack Dyer and Matty Lamb have lost three of their last five holes as 2UP beat Mac Meissner and Ricky Castillo.
There were eight individual matches in the afternoon session.
Fitzpatrick, the younger brother of English professional Matt, lost the last two holes in the match with Pierceson Coody, while Hammer escorted Murphy 3 and 1, and Castillo cruised to a 5 and 3 win against Ben Schmidt.
William Mouw escorted Ben Jones 4 and 3, and Eckroat won two of the last three holes to punch Flanagan.
But Power never lagged behind in his match and the 16th concluded a 3 and 2 victory. Lamb was similarly dominant in his 2 and 1 victory. Brown won by an equal margin, although his match with John Pak was not as direct.
Pak scored three holes from the 11th to equalize the match, but Brown took the next two before equalizing the win to 17.
Another round of fours follows on Sunday, followed by 10 individual matches. As a defending champion, the US needs 13 points to keep the trophy, while GB&I needs 13½ to get it back.
USA 7-5 GB&I
Saturday Four (US first)
Cole Hammer and Davis Thompson defeated Alex Fitzpatrick & Barclay Brown 1UP
Quade Cummins and Austin Eckroat lost to Mark Power and John Murphy 1UP
Mac Meissner and Ricky Castillo beat Jack Dyer & Matty Lamb 2UP
Stewart Hagestad and William Mouw lost to Angus Flanagan and Jack Bolton 1UP
Pierceson Coodydefeated Alex Fitzpatrick 2UP
Davis Thompson lost to Mark Power 3 and 2
Ricky Castillo defeated Ben Schmidt 5 and 3
William Sleeve they beat Ben Jones 4 and 3
Quade Cummins lost to Matty Lamb 2 & 1
Austin Eckroat defeated Angus Flanagan 1UP
John Pak lost Barclay Brown 2 & 1
Cole Hammer defeated John Murphy 3 and 1