Opponents Anna Davis and Kelly Xu fought back admirably, applying real pressure to the English pair as they reduced their deficit to one with three holes to play.
Yet a bogey from the Americans on the par-3 16th gave Fullbrook and Rhodes welcome breathing space before a par from the latter sealed a 2&1 victory on the 17th.
“It was maybe a bit more stressful than we would have liked, but we’re really happy,” said Fullbrook.
Lily Hirst and Davina Xanh unquestionably ran into the form pairing of the morning as they went down 4&2 to Romero and Talley.
The in-form American duo, who each shone at last week’s US Women’s Open, were eight-under-par for the first 11 holes and secured the first point of the match at the 16th despite Hirst and Xanh fighting back with wins at the 12th and 14th.
The final match of the morning went all the way to the 18th, with O’Keefe and Koo holding off a determined comeback from Nellie Ong and Charlotte Naughton.
O’Keefe and Koo were three up after seven but soon found themselves pegged back to all-square, before crucially nosing ahead again on the par-5 14th.
Ong was agonisingly close to converting a lengthy birdie putt on the 18th that would have really dialled up the tension. The ball slipped by, however, and O’Keefe then holed a putt of her own to earn a two up win and a 2-1 session score in favour of Meghan Stasi’s home team.
Coulter and O’Brien impress but US extend lead
All three afternoon contests shared a similar pattern; in each case a tense and evenly fought front nine was followed by one pairing seizing command after the turn.
The top match tilted emphatically in favour of McDonald-O’Brien and Coulter, who along with Rhodes was part of GB&I’s victorious team in 2024.