It turned out that Federer, who holds a 21-3 edge in head-to-head matches with Roddick, didn't last much longer. The Swiss superstar was overpowered by the hard-hitting Berdych, who forced Federer to make a number of uncharacteristically poor shots as he jumped out to a two-set lead.
Federer stormed back as he often has throughout his career, breaking his opponent at 3-2 - thanks in part to a Berdych double-fault - and coasting from there, punctuating his third-set triumph with an ace.
The two traded service games until they were tied 4-4. Federer stumbled on back-to-back points and Berdych seized the advantage, breaking the world No. 1 before serving out at love to reach the final four of a Grand Slam event for the third time in his career.
Berdych is now an impressive 4-3 in his last seven matches against Federer - and he told reporters after the match that he has a theory on his success.
''It's probably the way that, with my game, I'm able to make him some trouble. There is something in my game that he doesn't like, and it makes him a bit struggle, I would say, and maybe bring him out of his comfort zone.''
As for Federer, he surmised that it just wasn't his day:
''So many moments, I thought, 'Man, it's just not happening for me. It was just a very disappointing match for me.''
Berdych will face Andy Murray in the semifinals while Federer remains stuck on 17 Grand Slam titles. This is his earliest U.S. Open exit since 2003, when he was knocked off in the fourth round by David Nalbandian. Federer, of course, would go on to win the next five U.S. Opens.