Dundalk's Caolan Rafferty stopped a US fightback in its tracks to help Great Britain and Ireland take a 7-5 lead into the final day of the Walker Cup at Royal Liverpool.
After coming out of the morning foursome session tied at 2-2, the home side were on course to win seven points from the eight singles before the Americans battled back to lose the session just 5-3.
"It was a pretty good day," said home captain Craig Watson. "It could have been better, but we knew the Americans were going to come back to us. We're looking forward to tomorrow though.
"No matter what happens in the foursomes tomorrow, we still have to play in the singles. The boys will be up for it."
After wins on the 18th for Alex Fitzpatrick over world number one Cole Hammer, Euan Walker over Steven Fisk and Sandy Scott over US Amateur champion Andy Ogletree, the US claimed two big points in the middle of the order.
Portmarnock's Conor Purcell twice came back from two down to square his match with US Amateur runner-up John Augenstein, but he was never quite firing on all cylinders and lost 2&1.
Mallow's James Sugrue did not get to play in the foursomes, but after overcoming a nervous start to be two-up after six against John Pak, he fell on the 18th in cruel fashion after a dogfight.
Pulled back to all square through eight holes, just three of the last ten holes were halved, and Pak won four of them, going one up for the first time in the match when it mattered most, on the 18th.
It was a painful defeat for Sugrue who was one up with two to go after a brave four at the par-five 16th gave him the lead.
But he made a double-bogey at the 17th after driving into sand and then shortsiding himself in a greenside bunker in three, then lost the 18th to Pak's birdie three as he sized up a par putt that he had hoped might salvage a half.
A win for Conor Gough over Isaiah Salina coupled with a 4&2 defeat for Tom Sloman to Brandon Wu made Rafferty's point a key one.
The Dundalk stalwart looked to be cruising to victory when he went four up after eight holes to Alex Smalley.
But the tough closing stretch took its toll, and after being pegged back to one-up with just two holes to play, he was grateful to win the 17th with a bogey and clinch a 2&1 win in front of his Dundalk support.
"The four up lead early on was nice, and it gave me something to hang on to,” said the 26-year-old, who was an estimated six-over for the holes played.
"Then it was a real tussle towards to end - a couple of poor shots, a missed a short putt. But just to get a win and get a point on the board in my first Walker Cup is nice.
"It is great to have the support here. It definitely helps you when you have those one or two ropey holes. I got the win for them as well."
Purcell was disappointed to lose in the afternoon but after winning with Fitzpatrick in the morning foursomes, he was pleased to see the team finish the day in front,
"I got him back to all square twice and every time, I ended up going one down again and then two down," Purcell said.
"Momentum didn't seem to be with me and I missed a few shots, but it looks like the team is doing well."
GB&I skipper Watson opted to repeat his morning foursomes pairings again, leaving Rafferty and Sugrue on the sidelines.
But while it was a tough day for the Mallow man, Watson has faith in him and does not believe he will need an arm around the shoulder before he takes on left-hander Akshay Bhatia in the singles.
"No, I think James is fine," said. "We had five good foursomes pairings. We could have thrown the balls up, the ten guys, and been happy with any of the pairings they came out with, so we just went with no reason with the four we had this morning.
"But James is fine. He's had a great season, and he loves playing in front of the crowd, so I fully expect James to play well tomorrow.”
US captain Nathaniel Crosby .was relieved to go into the final day just two points down but knows that this match is on a knife-edge
"I think John Pak winning his match, we were pretty lucky to be 5-3 down when it looked like we could be 6-2 or even 7-1-down,” Crosby said.
“You know, I think that these guys have tremendous games. They've won a lot of golf tournaments to be here, and if they just play their games tomorrow, we'll see where the chips fall.”
47th Walker Cup, Royal Liverpool, Hoylake
Day 1 - Overall: USA 5, Great Britain & Ireland 7
USA 2, GB&I 2 (USA names first)
John Augenstein Andy Ogletree lost to Alex Fitzpatrick & Conor Purcell 2&1
John Pak & Isiah Salinda bt Sandy Scott and Euan Walker, Euan 2&1
Stewart Hagestad & Aksay Bhatia lost to Harry Hall and Conor Gough 2&1
Brandon Wu & Alex Smalley bt Tom Sloman & Thomas Plumb 2& 1.
Singles (USA 3, Great Britain & Ireland 5)
Cole Hammer lost to Alex Fitzpatrick 2 holes;
Steven Fisk lost to Euan Walker 2 holes;
Andy Ogletree lost to Sandy Scott 1 hole;
John Augenstein beat Conor Purcell 2&1
John Pak bt James Sugrue 1 hole;
Isaiah Salinda lost to Conor Gough 2 holes;
Alex Smalley lost to Caolan Rafferty 2&1;
Brandon Wu bt Tom Sloman 4&2.
Foursomes (USA names first)
08:00 John Augenstein & Andy Ogletree v Alex Fitzpatrick (Eng) & Conor Purcell (Irl);
08:10 John Pak & Isaiah Salinda v Sandy Scott (Sco) & Euan Walker (Sco);
08:20 Stewart Hagestad & Akshay Bhatia v Harry Hall (Eng) & Conor Gough (Eng);
08:30 Brandon Wu & Alex Smalley v Tom Sloman (Eng) & Thomas Plumb (Eng).
Singles (USA names first)
13:15 Salinda v Fitzpatrick;
13:25 Pak v Walker;
13:35 Wu v Scott;
13:45 Smalley v Rafferty;
13:55 Hagestad v Hall;
14:05 Ogletree v Gough;
14:15 Augenstein v Plumb;
14:25 Bhatia v Sugrue;
14:35 Hammer v Purcell;
14:45 Fisk v Sloman.