GB&I trailed by two in the singles before winning the final three matches to lead the USA 6½-5½ after a raucous opening day at Lahinch.
The Walker Cup reaches Lahinch for the first time, with GB&I chasing a first win since 2015 and 8,000 fans expected each day.
Jack Whaley, Stuart Grehan and Connor Graham headline GB&I’s 10-player team for the 51st Walker Cup at Lahinch on 5-6 September.
The GB&I Walker Cup team 2025 heads to Cypress Point as underdogs, with Dean Robertson leading ten hungry talents.