Heat, Roddick halt defending champ

MELBOURNE, Australia -- Novak Djokovic's hopes for a second straight Australian Open title ended under a broiling sun against Andy Roddick on Tuesday.

With ice packs and massages failing to provide relief, third-ranked Djokovic became increasingly woozy and was forced to retire while trailing 6-7 (3), 6-4, 6-2, 2-1, allowing the seventh-seeded Roddick to move into the semifinals.

The 26-year-old American will face second-ranked Roger Federer, now within two victories of a record-tying 14th Grand Slam after routing No. 8 Juan Martin del Potro of Argentina 6-3, 6-0, 6-0. Federer, with a 15-2 record against Roddick, ran off the last 13 games.

"Playing Andy is always nice," the 27-year-old Federer said. "We've had some big matches over the years and it's always a pleasure to play against him because he brings energy to the court with his serve and his character. It's nice to play somebody my age. Everyone's so young now."

Djokovic said he was cramping and sore, and "didn't really have time to recover" from his previous match, which ended at 2:26 a.m. Monday.

"Conditions were extreme today. It did affect more on me than him, as you could see," Djokovic said of temperatures that reached 95 degrees. "But, you know, that was the situation. I just have to cope with it. Really tried my best, but sometimes you can't fight against your own body."

Roddick, meanwhile, looked as fit as ever. After losing 15 pounds with a tough offseason workout regimen under new coach Larry Stefanki, he was quicker and his backhand stronger. The match left little doubt about the American's stamina on another sweltering day with not a cloud in the sky.

"It's rewarding to come out on a day like today, when it's pretty hot, and feel pretty good. That's what you do the work for," Roddick said.

While the crowd in the night match was definitely pro-Federer, it began backing the increasingly dispirited del Potro. But nothing could stop Federer, who won 51 of the last 65 points and finished with 38 winners to a mere nine unforced errors.

Everything was working for Federer. One service game in the first set summed it up -- ace, backhand winner, forehand winner, volley winner, all in less than two minutes. As he served for the second set, a fan shouted: "You're perfect, Roger!"

Not quite, but very, very good.

"For me, it's a fabulous effort," he said. "I'm delighted and hope I can keep it up."

Del Potro called it a bad day that showed he needs to improve to compete against the best.

"I can't do nothing in the match," del Potro said. "He play like No. 1 of the world."

The heat wasn't a major issue in the opening match, when Vera Zvonareva ran off 11 straight games in a 6-3, 6-0 win over 2007 Wimbledon finalist Marion Bartoli of France to reach the semifinals for the first time.

Seventh-ranked Zvonareva will meet fellow Russian Dinara Safina, who survived 11 double-faults and 36 unforced errors to beat Australia's Jelena Dokic 6-4, 4-6, 6-4 in a match with 11 service breaks.