BRISBANE, Australia (AP)—Andrea Petkovic and Angelique Kerber had straight-set wins on Saturday to give Germany a 2-0 lead over Australia in their Fed Cup semifinal and primed to reach its first final in 21 years.

Petkovic opened with a 6-1, 7-6 (7) win over Sam Stosur while top-ranked German player Kerber had little difficulty beating Casey Dellacqua 6-1, 6-0 in 51 minutes on outdoor hard courts at Pat Rafter Arena.

The reverse singles will be played on Sunday, followed by doubles.

Ashleigh Barty and Dellacqua, who reached three Grand Slam doubles finals last year, are expected to play doubles for Australia. But unless Stosur and Dellacqua both win their reverse singles matches against Kerber and Petkovic respectively, the doubles match will be meaningless.

Germany is trying to reach its first Fed Cup final since 1992, when it beat Spain for the title with now-captain Barbara Rittner in the side.

''I am very proud of my team, they played two great matches,'' Rittner said. ''The first was a lot closer than it looked, and the second Angelique just played a great match. I didn't expect us to be up 2-0 , I just wished ...''

Stosur once again had difficulty playing before her home crowd, where she admits she feels extra pressure. But the 2011 U.S. Open champion and 2010 French Open finalist is having a tough time everywhere this year, only making it past the third round at one tournament.

''I was kind of nervous but I just got through it,'' Petkovic said.

Unforced errors by Stosur handed Petkovic the first set, but the Australian led 5-3 in the second before allowing the German player to level at 6-6. In the tiebreaker, Petkovic had three match points at 6-3 but Stosur fought off those and another before Petkovic clinched it.

Petkovic suggested Stosur faced a ''tougher mental state'' before the home crowd, but the Australian said it didn't affect her.

''I wasn't overly nervous,'' Stosur said. ''She came out hitting the ball very clean and deep - that puts you on the back foot a little bit. At least I was able to fight back after a lopsided first set, but at the end of the day that doesn't really count for much.''

Two years ago, Australia upset Germany 3-2 in Stuttgart in a World Group encounter in which Stosur won both her singles matches.

''It was a very good match for me, I was there from the first point,'' Kerber said of her easy win over Dellacqua. ''It was a great feeling to go on court up 1-0, and now I'm even happier it's 2-0.''

It is Australia's first semifinal appearance since 1993, and now against heavy odds, the country is trying to win the Fed Cup for the first time since 1974 when seven-time Grand Slam singles champion Evonne Goolagong led Australia to victory.

Czech Republic and Italy are playing in the other semifinal this weekend. The final is Nov. 8-9.