Gleneagles, Scotland — Striking a psychological blow in the opening session of the Ryder Cup, the underdog Americans took down Europe’s big guns — Rory McIlroy and Ian Poulter — and grabbed a 2 1/2- 1 1 / 2lead after the fourballs on Friday.

Three rookies played a huge part in the U.S. resurgence.

In the morning’s last match, Phil Mickelson and Keegan Bradley won the final hole to beat McIlroy and Sergio Garcia 1 up to put the U.S. ahead for the first time. Mickelson, who made a short birdie putt on the 18th, and Bradley have won four fourball matches in a row together.

Mickelson and Bradley were 2 up after the 10th, but squandered the lead in windy conditions. A 10-foot eagle by Keegan at the 16th put them back on track.

“That gave us a huge momentum boost coming down the stretch,” Mickelson said. “Even though we fought it for a few holes, we were able to hang in there until it turned, and those shots that Keegan hit on 16 were just stupendous.”

It marks the fourth straight time Europe has not won the opening session. Despite that, Europe has won seven of the last nine Ryder Cups.

Justin Rose and Henrik Stenson gave Europe the first point, beating Bubba Watson and Webb Simpson 5 and 4. But then the American rookies came up big to swing the momentum, knocking off Poulter in the process.

In a stunning performance, 21-year-old Jordan Spieth and 24-year-old Patrick Reed — the youngest pairing in Ryder Cup history — beat Poulter and Scottish rookie Stephen Gallacher 5 and 4.

“It feels incredible,” Spieth said. “It was very quiet around our group today. It was a goal we had to achieve. It was nice to have a partner that was making everything he looks at.”

U.S. captain Tom Watson’s gamble of pairing the rookies in the first session paid off.

“It means a lot that he has trust in us,” Spieth said.

Watson had singled out Poulter as the one player the Americans wanted to target — even more than No. 1-ranked McIlroy. Poulter had won seven consecutive Ryder Cup matches and was the catalyst of Europe’s remarkable comeback in Medinah two years ago. This was Poulter’s heaviest ever Cup defeat.

“We couldn’t manage to get it done today, so it’s a shame,” said the Englishman, who went without a single birdie. “We don’t hole enough putts, that simple.”

The third American rookie, 35-year-old Jimmy Walker, also had a big morning, making a birdie putt at the 18th to halve the match against Thomas Bjorn and Martin Kaymer. Walker and Rickie Fowler had been trailing the entire match.

Walker and Fowler were 3 down after four holes but kept chipping away. Walker holed a bunker shot for an eagle at the 9th.

“We kept giving ourselves good looks at it,” Walker said. “We were in good shape.”

Watson said he was proud of his rookies, but decided not to send them out for the afternoon foursomes.

“I said, ‘I know you’re going to be mad at me, but you’ll be playing tomorrow for sure,’” Watson said.

Watson retained the Mickelson-Bradley pairing for the foursomes. They faced Graeme McDowell and French rookie Victor Dubuisson in the fourth match. Watson also brought in veterans Jim Furyk and Matt Kuchar, who were up against Lee Westwood and rookie Jamie Donaldson.

Europe captain Paul McGinley stuck with McIlroy and Garcia, who were pitted against Walker and Fowler. Poulter and Gallacher missed out.

The day began amid a raucous soccer-style atmosphere, with Simpson badly mishitting the opening tee shot.

The veteran course announcer, Ivor Robson, even slipped up, mistakenly introducing Simpson as Bubba Watson.

Seconds later, Simpson got under the ball and hit a three-wood high into the air. The shot traveled about 190 yards, barely reaching the fairway.

Then Bubba Watson tried to rile up the crowd, as he had at Medinah, cupping his hand to his ear and waving to encourage more noise from the heavily outnumbered U.S. fans. With cheers ringing out, he hit his drive into the left rough.

European fans chanted “10-6 — and you still can’t win,” a reference to the American collapse in Medinah.