Dancevic, ranked 109th in the world, waited out three rain interruptions to defeat Russian Igor Kunitsyn 6-4, 7-6. The match ended nearly nine hours after it began.

The 22-year-old, who has never been this deep in an ATP tournament, will face Roddick, who beat sixth-seeded Korean Lee Hyung-taik 6-3, 6-7, 6-1 in the only other match that got on court.

Roddick fired 16 aces, including three in the concluding game, to go through in 90 minutes.

"I'll take what I can get," Roddick said. "The only thing I'm a bit disappointed with was not taking my chances in the second and closing it out there."

The atrocious weather forced two quarterfinals to be postponed to Saturday.

Defending champion and second seed James Blake will face off against California teenager Sam Querrey while Russian third seed Dmitry Tursunov plays amateur Kei Nishikori of Japan.

Winners of those matches will have to double up on Saturday to try and reach the Sunday final.

Dancevic and Kunitsyn were interrupted for nearly four hours after the ninth game of their opening set and sat out another marathon of three hours in early evening.

The Canadian came from 1-5 down in the second set, a miracle finish which he could barely comprehend.

"I really don't know how I won the second set," he said. "I was down the whole time.

"I'm feeling pretty lucky this week."

The victory avenged a loss to Kunitsyn in February at Las Vegas and made Dancevic the first from his nation to reach an ATP-level semi-final ATP since Sebastien Lareau in Memphis in 2001.

Roddick improved to 9-1 over Lee and moved a step closer to another title at an event he won in 2003 and 2004. Roddick is chasing a second title of 2007 after winning Queen's in June.