Sheils Donegan, who was in the thick of his own contest with Tyler Watts, a match he won 3&2, said the roars from the moment Grehan’s winning putt dropped could be heard reverberating around the course.
After trailing early in the match, the Scot turned things around in the back nine and says he was buoyed by the noise from up ahead.
“You can really tell when there is something going on ahead of you,” he said.
“We’re walking down 13 and you just hear the biggest roar of your life over on 18. I go to my caddie, ‘I think Stuart just won that’.
“I think it is amazing to hear those cheers from across the golf course. It just gives you that little extra boost of energy when you might be a little bit down, or you just want a little bit extra momentum.”
After Grehan claimed the first singles point of the afternoon for GB&I, the visitors bounced back quickly and secured three points in succession thanks to Fang winning by one hole over Jack Whaley, Jay Leng Jr defeating Tyler Weaver 2&1 and William Jennings also edging out Connor Graham by one hole to take the lead in the match for the first time at 4½-3½.
Stewart Hagestad extended his remarkable singles record in the Walker Cup to notch up his eighth win out of nine singles matches by overcoming Ben Bolton 2&1.
Despite the two-point deficit, GB&I rallied to secure the final three points of the session and lead the match overall at 6½-5½. After Sheils Donegan won his point, Eliot Baker followed up with a victory by the same margin against Josiah Gilbert before Luke Poulter rounded proceedings off by beating Miles Russell 2&1.