Roddick had 33 aces Saturday, the final one on match point. He improved to 9-0 against Melzer, and he's 22-3 this year in tiebreakers.
Roddick, seeded sixth, was runner-up at Wimbledon to Roger Federer in 2004 and 2005.
How does his play in those years compare with this week?
"I think the best I've played here was probably '04," Roddick said. "But as far as comparing to '05, it's probably similar."
Berdych has yet to drop a set through three matches, and he's 2-2 against Roddick, winning the last time they played -- at Tokyo in October.
"Berdych is streaky," Roddick said. "It's rarely middle-of-the-road. He's either really good or not so good. Right now you expect to get the best of him, with the way he has been rolling through the tournament so far."
Meanwhile, Andy Murray completed another comfortable win, this time against Viktor Troicki of Serbia 6-2, 6-3, 6-4.
Murray saved the only break point he faced in the match and hit 37 winners, sealing the win with an ace.
Murray, bidding to become Britain's first men's Wimbledon
singles champion since Fred Perry before World War II, appeared
in a hurry to get off court as light rain threatened to force
the use of the new roof for the first time during a match.
Troicki offered a little more resistance in an entertaining
third set but Murray was never troubled as he moved through to
face Swiss number two No. 19 Stanislas Wawrinka on Monday.
"I'm very happy I won the three matches this week," said
Murray. "I hope that I can keep it
going next week because my performances were pretty solid."
"[The expectation] is just one of those things you have to
get used to dealing with. It hasn't troubled me this week. I'd
be very surprised if it did next week."
"It has never happened to me that we stopped playing at six-all in the fifth," Haas said. "We should have a tiebreak at six-all like in the U.S. Open. When you've played so much tennis ... it's really draining."
American Jesse Levine's best run at a major event came to an end. The last qualifier in the men's draw, Levine faced 23 break points and lost to Wawrinka 5-7, 7-5, 6-3, 6-3.
With some amusing chants ringing in his ears, including
adapted versions of popular songs by the Beatles, Gary Glitter
and Frankie Valli, Hewitt broke Petzschner's resolve in the
third set and clinched the win on his third match point.
Hewitt will play 23rd-seeded Radek Stepanek for a place in the
Elsewhere No. 8 Gilles Simon and 2003 French Open Juan Carlos Ferrero also advanced. Ferrero, a former No. 1 now ranked 70th, needed a wild-card invitation to get into the field, but he beat No. 10 Fernando Gonzalez 4-6, 7-5, 6-4, 4-6, 6-4 on Court 1 as a light rain fell.
There was some consideration given to moving the conclusion of that match to Centre Court, where the new retractable roof was closed, just in case. But Ferrero and Gonzalez finished, and the roof has yet to be used as a barrier against wet weather.
Information from Reuters and The Associated Press was used in this report.