Earlier in the day, Agassi produced yet another magical comeback to beat Germany's Rainer Schuettler 5-7, 6-0, 6-4 and leave himself on the brink of capturing his first Masters title since his debut at the year-end finale 13 years ago.
In a ruthless performance, the 22-year-old Swiss needed just 62 minutes to crush the hopes of an all-American final, humbling a helpless Roddick in front of his home fans.
A perfect 4-0 heading into Sunday's final, one more win will not only give Federer his seventh title of the season and the winner's purse of $1.52 million but will push the Swiss up to number two in the world rankings ahead of Spain's Juan Carlos Ferrero.
"I'm playing for something, I'm not stuck at number three, I still have room to improve," Federer said, after improving his head-to-head record against Roddick to 5-1. "
"And that's nice, it adds a little extra motivation."
"But in general, just being at the Masters motivates me."
Roddick, who had spent the week prior to the final in New York rehearsing for his guest host role on "Saturday Night Live", had looked far from his best at the Westside Tennis Club, never quite finding the form that had catapulted him to the top.
His trademark thundering serve silent and his usually punishing ground strokes missing the mark, the U.S. Open champion was left fully exposed and vulnerable to the clockwork precision of his stylish opponent.
In a near flawless display, Federer never faced a break point the entire match, whistled 30 winners by Roddick while committing just 13 errors and adding insult to injury out-aced the American 12-5.
MORE FLAIR
"He (Federer) really doesn't have any big weaknesses, especially when he serves the way he did tonight," Roddick said.
"I just felt like he was a step faster than I was today."
"The guy just has more natural flair and talent for the game than most."
The first set unfolded as one would expect between the world number one and number three, neither player earning a break point.
But in the tiebreak Federer began to stamp his authority on the contest winning decisively 7-2.
The first break point of the match would come in the fifth game of the second set and it would go to Federer, the Swiss seizing his opportunity launching a laser backhand down the line to go in front 3-2.
He then stormed through the final four games to clinch the match.
"I definitely think this was my best match so far," Federer said. "I was solid from beginning to end.
"I'm happy with my performance this whole week but it's not over yet. I still have to play one big match."
In Sunday's final, Federer will carry a considerable age advantage on the 33 year-old Agassi as well as a slight edge in confidence having registered his first career win over eight-time grand slam winner in the opening match of round-robin play.
But Agassi, playing in his first event since a semi-final loss at the U.S. Open, has displayed unparalleled determination and resilience this week as he looks to end the season on a high note.
Photograph: Reuters
