Roddick reached match point by hitting a forehand return that kissed the net cord twice before landing for a winner, and he then smacked one last service winner to beat Thomas Johansson (search) 6-7 (6), 6-2, 7-6 (10), 7-6 (5) Saturday.
Federer, the top-ranked Swiss who defeated Roddick in last year's final, advanced to Sunday's final by beating Lleyton Hewitt (search) on Friday. Federer needs one more victory to join Pete Sampras and Bjorn Borg as the only men since 1936 to win three consecutive Wimbledon titles.
Roddick, seeded second, is 32-2 on grass since 2003. Both losses have been to Federer at Wimbledon.
The second semifinal was on serve in the first set Friday with Roddick leading 6-5 when showers forced play to be suspended overnight, and the match resumed 20 hours later.
Roddick squandered two set points to lose the opening set and overcame three set points in the third-set tiebreaker. The only mini-break in the last tiebreaker came on the next-to-last point, when Roddick's slice return skipped over the net cord. He walked away from the point with his right arm raised, the traditional gesture of apology for a luck bounce.
He won the match with one more swing, sank to his knees and raised his hands. Roddick improved to 16-5 lifetime in tiebreakers at Wimbledon.
As usual, Roddick relied on his dominant serve — he made 75 percent of his first serves and hit 61 unreturned serves, including 19 aces. He was broken just once, and for the second straight round had no double-faults.
But Roddick also won thanks to his best net play of the tournament, aggressively moving forward and also laterally. He dove to the well-worn lawn attempting volleys at least twice, a la Boris Becker, and put away a nifty volley on the run after a shot by Johansson deflected off the net cord.
The Grand Slam final will be Roddick's first in a year. The 2003 U.S. Open champion is bidding for his second major title.
Johansson, a 30-year-old Swede, came up short in his bid for a second berth in a Grand Slam final. He won the 2002 Australian Open.
When the first set resumed shortly after high noon on a cool, cloudy day, Johansson held for 6-all, and Roddick then played a nervous tiebreaker. His big serve helped him earn two set points at 6-4, but the No. 12-seeded Johansson won the next four points — two with baseline winners and two on errant Roddick forehands.
Roddick rebounded quickly, moving forward with success to break twice for a 4-0 lead in the second set.
When Roddick broke for a 6-5 lead in the third set, he threw a fist and shouted, "Come on! Let's go! Yes!" But he made three groundstrokes errors in the next game, and Johansson ripped a backhand winner for his only service break.
The match swung Roddick's way when he won the second tiebreaker. He erased one set point when Johansson sent a forehand long to end a 14-shot rally for 6-all. After Johansson won the next point, Roddick gambled by playing serve-and-volley, placed one shot on the line and then put away a slam for 7-all.
Johansson reached his final set point at 9-8, but Roddick answered with his 15th ace. Four points later Roddick closed the tense 68-minute set with a 133 mph service winner.
The challenge will be even more formidable Sunday for Roddick, who's 1-8 against Federer, including losses in their past four matches.
Federer went into his match against Hewitt 0-2 in Grand Slam semifinals this year. But the first Wimbledon semi since 1989 to involve the two top-ranked men turned out to be a mismatch.
Federer rarely ventured to the net, content to win with a dominating serve, pinpoint groundstrokes and his knack for coming through on pivotal points.
"I believe strongly in my capabilities," he said. "I'm very motivated. There's a lot of confidence as well with my record on grass and in general over the years. I've built up this feeling on big points that I can do it over and over again."
Federer extended his winning streak on grass to 35 matches — six shy of Borg's record 41, set in 1976-81. The streak includes 20 matches at the All England Club.
He's nearly as good on other surfaces, with a record of 97-5 since June 2004.
"I'd be surprised if he didn't win 10 majors," said John McEnroe, who won seven. "He's just better than everyone else. ... He's closing in on being one of the best, if not the best of all time."
The quality of the opposition provided some consolation for Hewitt, beaten for the fourth time in his past six major events by Federer.
"I'm obviously doing right to keep putting myself in these positions," Hewitt said. "It would just be nice to go one or two steps further. ... I can't really remember the last time in the last 18 months or so that I've lost a bad match to an average player. So in that way, that's a huge positive."