MELBOURNE, Australia — One could forgive Andy Roddick for believing he was closing in on Roger Federer. Two times he played Federer tight last fall, and he had beaten the world no. 1 at an exhibition this month and during practice since. Among fans, commentators, coaches, and players there was a sense, before Thursday evening’s semifinal at the Australian Open, that the American would make a statement.

Instead, it was Federer who spoke — very loud and very clear — and Roddick who was left speechless. The 25-year-old Federer might be vulnerable at exhibitions and on the practice courts, but at the game’s most prestigious events he remains all but untouchable. After Roddick won four of the first seven games, Federer won the next 11. In one stretch, he took 16 of 17 points, including 13 in a row. Nine of those points ended with clean winners. In the second set, Roddick won six points, and for the match he lost more points (36) on his serve than he won (29). Federer won all seven of his break points, and hit as many winners, 45, as Roddick won points. He even mastered the instant-replay challenge system that has so often befuddled him, succeeding on all four of his attempts. This was the thrashing of thrashings, 6–4, 6–0, 6–2 in 83 minutes. It awed everyone who witnessed it, including Federer.

“It’s just unreal,” he said moments after the match. “I’m shocked myself, I don’t know what to say.”

Mats Wilander, the former world no. 1 and winner of seven major titles, did.

“Frightening,” he said. “I’ve never seen anything like that.”

“Bone crushing,” Jim Courier, also a world no. 1 and winner of four Grand Slam titles in his day, said.

Wilander suggested canceling Federer’s postmatch press conference. ” What is there to talk about?” he asked. Instead of broadcasting highlights of the entire tournament, he said, Australian television should “just show that match.”

Roddick was not in a talkative mood in the early goings of his chat with reporters, but to his credit, he loosened up and did not play down his defeat.

“It was miserable,” he said. “It sucked. It was terrible. Besides that, it was fine.”

Asked how Jimmy Connors, Roddick’s coach, reacted, Roddick said, “He gave me a beer.”

What chance did the winner of Fernando Gonzalez and Tommy Haas, the other two semifinalists, have against Federer? “Slim.”

Would he be able to sleep after a loss like this? “It depends on how much I drink tonight.”

Federer’s coach, Tony Roche, was more diplomatic.

“Roger was certainly up for it, there’s no question about that,” Roche said. “It was a combination of him playing unbelievable and Andy not at his best.”

As for Federer, there’s not much a man can say when asked for his thoughts on a performance so obviously astounding. (He can’t well credit the weather.) Federer has a knack for saying immodest things modestly; perhaps he comes off that way because his achievements are so absurd. So it was when he reminded reporters that the tournament wasn’t over yet, that he still had one more match to play, while admitting that the memory of this victory is one he’ll cherish.

“I’ve played good matches here, but never really almost destroyed somebody,” Federer said. “For me, that’s a highlight of my career to do it right here tonight, so I’m very, very happy about it.”

Federer would not say that he had hoped to serve notice on Roddick, and the rest of the field, with a convincing victory. There’s no doubt he heard all the talk. This world no. 1 reads the papers and watches tennis on television, and news of Roddick’s improvements, and his growing confidence, was everywhere. Though Federer had won 12 of their first 13 meetings, Roddick did some damage at the U.S. Open and held three match points at the Masters Cup in Shanghai before losing. His performance this month, practice or not, strengthened his resolve.

When answering questions in French, Federer said he played a lot of serve-and-volley in the exhibition match because he did not want to give Roddick too much information about his game leading up to the first major of the year. He also said he was genuinely nervous about the prospects of this encounter.

He looked tight at the start, breaking serve but giving the break right back. But once he broke for a 5–4 lead, he was a blur, and Roddick became a member of the audience. Over and over he came to the net, only to observe another passing shot, each one prettier than the last. On the first point of the third game in the second set, Federer was at his most astounding, using a backhand halfvolley at the baseline to deflect a powerful Roddick forehand for a cross-court winner. As Federer got better, Roddick got worse. When he tried to hit a ball into the stands after falling behind 5–0 in the second set, his racket slipped and nearly hit a photographer.

Asked what it felt like out there — to be in such supreme, effortless control on every point — Federer couldn’t give an exact answer.

“You don’t ask yourself any more questions,” he said. “You forget about how tough the beginning was, you know, of the match. There’s no explanation. That just happens.”

It doesn’t happen quite like that to anyone else.

tperrotta@nysun.com