"It's historic for us beating a team of Italy's level and it's a very good win," Klinsmann said. "But what we wanted to do above everything was to learn, to see how we could do against a team like Italy. I think the boys did very, very well, they played great for 90 minutes. And moreover we have young players and they're growing and it's from games like this that they do."
Italy almost snatched a draw in stoppage time when Riccardo Montolivo's effort flashed past the right upright. It is the Azzurri's first defeat in Genoa since 1924, and came despite the hosts creating a majority of the chances.
"With this spirit we'll have a great European Championship. I'm absolutely not worried," Italy coach Cesare Prandelli said. "I have a lot to think about ahead of the Euros and I'll take the best things from this game the will to win, the determination, the fight to get back. ... So it's not a 'lost' friendly match. There's a lot to take from this. I'm sure I'll have the team ready by the summer."
The atmosphere in the Stadio Luigi Ferraris was very different from the last time the arena hosted a match, when Italy was awarded a 3-0 win over Serbia in European Championship qualifying after the game was called off in the seventh minute following crowd trouble from the visiting fans.
There was no sign of such trouble on Wednesday and a sizable American contingent added to the lively atmosphere. Former baseball great Mike Piazza was among the 15,000 fans, alongside Brian McBride who was left with a bleeding face following an elbow by Daniele De Rossi during a 2006 World Cup match.
Klinsmann had most of his regulars back after playing with a backup squad in victories over Venezuela and Panama. He had hoped to be able to pair Dempsey with Landon Donovan for the first time since taking over as coach last year, but the Los Angeles Galaxy forward pulled out of the squad Sunday with bronchitis. Jermaine Jones also withdrew with a strained right calf, and the two were replaced by Sasha Kljestan and Brek Shea.
Klinsmann singled out the 22-year-old Shea for special praise.
"He's one of the biggest talents we have," Klinsmann said. "He's special and that's why I sent him last season to Arsenal to learn under Arsene Wenger. The three weeks he spent there were very useful to him.
"But we're building him one step at a time. He's definitely one to watch and build over the next few years. This is a growth period of time that's not going to happen overnight."
Italy had its own personnel problem, especially up front where it was missing injured forwards Giuseppe Rossi and Antonio Cassano. Manchester City striker Mario Balotelli was left of the squad because of his fiery temper and unpredictability.
Italy almost got off to the perfect start when Nocerino launched a long ball toward Alessandro Matri, but goalkeeper Tim Howard rushed out and cleared the danger along with Steve Cherundolo.
Italy had another chance when Christian Maggio found some space on the right flank but his cross in was intercepted by Chievo midfielder Michael Bradley.
The Azzurri's first effort on target came in the fifth minute as Howard stopped Thiago Motta's weak effort.
The Americans' first sight of goal came when Fabiano Johnson slotted the ball across to Shea who fired well wide of the right post.
Italy did have the ball in the back of the net in the 26th minute but Matri's goal was ruled out for offside.
Italy also went close seconds before halftime. Nocerino's cross in was cleared by the U.S. defense but straight to Motta who lashed in a fierce effort which Howard did well to stop.
The U.S. stunned Italy 10 minutes after the break when Jozy Altidore kicked Bradley's cross out to Dempsey and the Fulham striker lashed in a fierce shot from just outside the box which flew past Buffon's outsretched hand and into the bottom left corner. It was Dempsey's 25th goal in 83 appearances.
"Initially, I was going to stay where I was and have him lay it back to me," Dempsey said. "I saw the guy was covering. So I tried to move to my right to try get open so he could play me the ball. He did a great job of holding it up, playing me, and I just tried to hit it low and hard, far post, and it went in."
Italy reacted by bringing on Roma forward Fabio Borini for his international debut and Inter's Giampaolo Pazzini. The U.S. also introduced a debutante as Terrence Boyd made his first appearance despite not yet having played a first-team club match for Borussia Dortmund.
Borini almost scored for Italy with his first touch for his country but Howard stopped the youngster's stinging effort from the edge of the area.
Italy upped the pressure on the U.S. goal as the half went on, but never really looked like scoring until Pazzini set up Montolivo for a good chance in stoppage time.
It is Italy's second defeat in a row, following November's 1-0 loss to Uruguay in Rome.