Sweden's Joachim Johannson left Andy Roddick shellshocked after beating the defending champion in five sets on Thursday to reach the U.S. Open semi-finals.

After Andre Agassi's hopes were ended by Roger Federer earlier in the day, Roddick was left to fly the American flag but he lost 6-4, 6-4, 3-6, 2-6, 6-4 in an explosive match featuring 64 aces.

It is the first time since 1986 that no American has reached the last four of the men's event here.

Second seed Roddick, who blazed through his four previous matches without losing a set, fell two sets behind as the 6-foot-6 Johansson let rip with lethal serves and forehands.

Roddick, who cracked 34 aces to Johansson's 30, hit back to win the next two sets and with the fans going crazy he looked ready to pull off a stunning rally.

But Johansson, 22, a former junior doubles partner of Roddick, showed remarkable calm in the storm, staving off break points in the first game and then at 4-4.

The Swede then went 40-0 up as Roddick served to stay in the championships and held his nerve to clinch victory on his third match point as the American hit a backhand long.

The 28th seed, who goes out with Lleyton Hewitt's sister Jaslyn, now plays the Australian fourth seed for a place in the final after the 2001 champion thrashed Germany's Tommy Haas 6-2, 6-2, 6-2.

"You can't pick your brother but you can pick your boyfriend, so I hope she'll be supporting me," Johansson told reporters following the first five-setter of his career.

"I was supposed to be playing golf with my dad in Scotland this weekend but I'll have to change my plans now."

Roddick said the match hinged on a few points.

"He converted and I didn't, that's pretty much it," said Roddick. "But you've got to give credit to him, he serves out of a tree.

"I don't feel good, if there was a flight out of La Guardia in 20 minutes I'd be on it."

Earlier, Agassi's dreams of a third U.S. Open title were left in tatters as Federer proved why he is the world's best player.

As Wednesday's rain was replaced by a swirling breeze, top seed Federer returned to complete a 6-3, 2-6, 7-5, 3-6, 6-3 win and clinch a semi-final against Tim Henman.

With a vicious crosswind playing havoc, Australian Open and Wimbledon champion Federer showed that behind the cool persona and flowing groundstrokes is a core of steel.

The Swiss, bidding to become the first player since Swede Mats Wilander in 1988 to win three Grand Slam titles in the same year, held a two sets to one lead overnight.

But Agassi, 34, launched a stirring fightback to break Federer's serve in the eighth game of the fourth set and level the match.

VICIOUS WIND

The fifth set became a war of attrition and it was Agassi, playing in his 12th quarter-final here, who cracked first.

He sent a forehand long in the eighth game to hand Federer a break and the Swiss player served out for the match.

"It was unbelievably windy," Federer said. "I had one game where I served three or four double faults and completely lost my game.

"In the end it was just a case of waiting for your opponent to make a mistake."

Agassi, though, vowed to return.

"Contrary to what it seems like you're hearing, I (have) never had an intention not to play," he told reporters. "My game plan is to play until I can't do it.

"I came here expecting to make somebody play a great match to beat me," added the 1994 and 1999 champion. "I mean, there's only so much you can do, you just gotta hope it falls your way."

EARLY SETBACK

Henman shrugged off an early setback to reach the semi-finals for the first time with a 6-1, 7-5, 5-7, 6-2 triumph over Slovak Dominik Hrbaty after their match was also interrupted the previous night.

The Briton was close to victory on Wednesday, cruising two sets up before rain fell.

He held serve at 4-5 in the third when play resumed but two games later a netted approach gave Hrbaty the set and a glimmer of hope.

But Henman, 30, quickly regained control, breaking the Slovakian twice to advance.

"I'm very excited about reaching my first semi-final in New York and playing Federer will be a pretty special match," said Henman, who holds a 6-2 head-to-head lead over the Swiss.

Hewitt maintained his flawless progress through the draw, making only 10 unforced errors against a demoralised Haas.

"I was just trying to pressure him and make him hit an extra shot each time," said Hewitt, who is yet to drop a set at this year's championships. "I could sense that he wasn't enjoying it out there."