The Associated Press

Birdie putts kept falling, one on top of the other, until the Americans finally secured a Saturday lead in the Ryder Cup for the first time since 1995 to set up a final day that finally matters.

The last hour defined the pressure and passion of the Ryder Cup, so intense that players on both teams were emotionally exhausted.

All that remains are 12 singles matches Sunday to determine the winner.

Robert Karlsson concluded a gripping afternoon at Valhalla with his seventh birdie in 10 holes as he and fellow Swede Henrik Stenson scratched out a halve against Phil Mickelson and Hunter Mahan.

The Americans hung on for two key halves to split the afternoon fourballs session, taking a 9-7 lead to finally give them a fighting chance to wrest the 17-inch gold chalice away from Europe.

‘‘The golf has been incredible,’’ U.S. captain Paul Azinger said. ‘‘My stomach is just churning.’’

Ian Poulter’s eyes nearly popped out of his sockets after making a 30-inch birdie putt that looked like 30 feet. Poulter arrived as a controversial captain’s pick, but he was the only European to play all four matches and he delivered three vital points.

Steve Stricker showed why his selection for his first Ryder Cup was a no-brainer. His match looked like a lost cause until Stricker escaped from the weeds and sank a 15-foot birdie putt on the final hole for a halve.

One minute the Americans looked as if they might build their largest lead in nearly 30 years. The next minute, it looked as though they might not have the lead at all.

‘‘It’s a bumpy road at times, isn’t it, to get to a victory,’’ European captain Nick Faldo said. ‘‘So you come off the road a bit, and we’re back on the road again now.’’

Europe has built overwhelming leads the last two times, practically icing the champagne on Saturday night.

Hold onto your tops.

‘‘It was amazing golf,’’ Azinger said. ‘‘It’s amazing because there’s so much pressure here and so much tension and you see in pressure situations the best performance in sports. A two-point lead is great.’’

The Americans need 5 1/2 points from the 12 matches Sunday to win the Ryder Cup for the first time since 1999. The intensity should return quickly, with Anthony Kim and Sergio Garcia leading off, two explosive players in their 20s.

Faldo put two of his strongest players at the end — Lee Westwood in the 11th match against Ben Curtis, and double major winner Padraig Harrington as the anchor against Chad Campbell.

The entire American and European teams huddled on the grassy slopes surrounding the 18th green at Valhalla as the final match trudged up the fairway, the ninth time in two days that a match came down to the final hole.

Hunter Mahan, unbeaten in all four matches in his Ryder Cup debut, hit his approach to the collar of the green for an eagle attempt from 20 feet. Karlsson followed with a second shot in the par 5 that settled 12 feet behind the hole.

Both narrowly missed. Both teams exhaled.

‘‘That’s an unbelieveable two days,’’ Poulter said. ‘‘I think we got a huge piece of momentum today, and the guys are pumped — proper, proper pumped. This is what the Ryder Cup is all about.’’

Some of the American rookies found that out.

Boo Weekley toned down his celebration until after his great shots, and there were plenty. Kentucky native J.B. Holmes delivered a putt that put the U.S. team up over Westwood and Soren Hansen, but Weekley stole the show.

He holed a 25-foot putt off the back of the 14th green green for a 2-up lead, then hit a bunker shot to 2 feet on the next hole. Asked where he would rank that shot among the top 10 of his career, Weekley replied, ‘‘I reckon No. 9. I done had eight holes-in-one.’’

They won on the 17th hole when Westwood failed to extend the match with a 15-foot birdie.

It was the first time in six years the Englishman lost a Ryder Cup match, an unbeaten streak of 12 matches that left him tied with Arnold Palmer and more disappointed for the team than himself.

‘‘The Ryder Cup is not about individuals,’’ Westwood said. ‘‘It’s about the team.’’

The rest of the afternoon was a highlight show.

—With the match all square, Karlsson poured in a 12-foot birdie putt at No. 14, and Mickelson followed him in from 10 feet.

—Jim Furyk hit his approach on the 15th within inches of the cup and it looked as if he and Kenny Perry would square their match against Poulter and Graeme McDowell. But McDowell knocked in a nervy 5-footer for birdie.

—Garcia knocked in a 35-foot birdie putt up the ridge on No. 8, screaming, ‘‘Come on! Come on!’’ when it fell. The quiet Stricker then topped him with an 18-foot birdie, and in a rare display of emotion, lunged forward and pumped his fist.

—Karlsson was 4 feet away for birdie on the 16th when Mahan dropped a 10-footer.

It was like that all afternoon, while Michael Jordan was busy text messaging with Tiger Woods, who surely missed out on the action.

Azinger ripped off his cap in celebration and crossed his fingers before every putt, showing nerves that he swore he wouldn’t have.

Faldo, meanwhile, must have felt vindicated.

The BBC roasted him throughout the morning for leaving out Westwood and Garcia, the European tandem that hardly every loses, and sending out what appeared to be a sacrificial lamb in English rookie Oliver Wilson and Stenson.

They faced Mickelson and Kim, fell four holes behind after six holes, but rallied to tie the match six holes later. With a 1-up lead on the 17th, Wilson holed a 30-foot birdie putt to win the match.

Trailing by three points after the first day, Europe won two foursomes matches and halved another in the morning to pull within two points, winning its first session of the morning. After a split in the afternoon, it comes down to Sunday.

Singles traditionally has been the Americans’ strength, but no longer.

Europe has the stronger team based on the world ranking. Europe has the won the last three Ryder Cups, and five of the last six. And Europe has trounced the Americans in singles the last two times.

But that was when it held a comfortable lead. For the first time since 1995, they have some catching up to do.