Lahiri sunk 16 and 19 footer putts on 16th and 17th holes before being conceded a four footer for par at the 18th. His partner, rookie Si Woo Kim also won his first points in the event last night.
The first of those two putts gave the Internationals the lead 1-up and the second kept it intact. On the 18th, Lahiri facing a four-footer -- similar to the one he missed two years earlier in Korea -- did not have to make it as the Americans conceded the par putt and the match.
"The monkey is off my back," said a relieved Lahiri. "It was really hard. I think that one full point has been quite elusive this week. It was nice to get the job done.
"Obviously it's been a tough week for the team, so we were trying our hearts out. Si-Woo played great and carried me for the first 15 holes. I stepped up today and we combined well. It was nice to come up with a full point."
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The Americans, who were up 8-2 after first days, today went to 11.5 points after winning the morning foursomes 3.5- 0.5.
Apart from Lahiri and Kim's success, the only other earnings for the day was the half point, Louis Oosthuizen and Branden Grace got from their match with Justin Thomas and Rickie Fowler in the morning session.
The score is 14.5 to 3.5 with 12 singles on Sunday. US need just one point a win or two halves, while Internationals need a near-sweep for an improbable win.
"When we started out on the first hole, I just told him we have to keep our head down and try to not look at the TVs. Because it's one of those weeks where you look up, and you see, you know, another American hole-out or a big putt made or a putt missed. You kind of put more pressure on yourself."
About the start this morning, Lahiri said, "I was sitting in the morning when I came in, and I said one of us or some of us have to make those putts and make those birdies coming home. I guess that was just a good seed in my head when I started out today.
Kim was the man for Internationals for almost 15 holes. Despite numerous lip outs, Kim still holed some crucial putts, including a 26-footer on fourth. Lahiri and Kim led 1-up after the ninth.
Then the Americans came back, as they have around the turn all week. Trailing by one hole, Hoffman and Chappell turned the tide once again to go one-up with some great golf between 10th and 14th.
Then the drama began. Lahiri hit his wedge to 16 feet on the 16th and after lots of missed chances this week he drained it to go 1-up.
On the next hole, Hoffman failed to make the green but chipped in from 65 feet and there were massive celebrations in US camp. Hoffman and Chappell ran into hug each other. That left Lahiri a 19-footer to halve the hole and save the lead. He did it and gave his own 'thumbs up' as the crowds first went silent and then applaued wildly.
Chappell sank a nine-footer for par on 18th, while Hoffman holed his four-footer. Kim gave up after going bunker to bunker. All this while, Lahiri's ball was marked four feet five inches from the hole. Just as he went to putt, the Americans gave it to him and conceded the match.
The US have been so dominant this week that they have lost just two matches on Thursday, Oosthuizen and Grace beat Daniel Berger and Brooks Koepka and on Saturday Lahiri and Si Woo beat Hoffman and Chappell. Three matches have been halved and the rest won by US.