Safina came within a point of defeat for the second consecutive match, then rallied past fellow Russian Elena Dementieva 4-6, 7-6 (5), 6-0. The semifinal berth is the first in a major tournament for the younger sister of two-time Grand Slam champion Marat Safin.
"I was one step away (from losing),'' Safina said, "so I'll be especially glad to be back tomorrow.''
Her latest comeback was remarkably similar to the one she mounted against top-ranked Maria Sharapova in the fourth round.
The No. 13-seeded Safina trailed Dementieva 5-2 in the second set and faced a match point in the next game, but Dementieva dumped a return into the net. That triggered a sudden reversal, and Safina lost only one game the rest of the way.
Against Sharapova, Safina also lost the first set, trailed 5-2 in the second and faced a match point in the next game.
Her opponent Thursday will be another Russian, 2004 U.S. Open champion Svetlana Kuznetsova.
"Dinara is playing very well,'' Kuznetsova said. "She has too many lives, so I have to be careful with her.''
Kuznetsova recovered from her own slow start to beat unseeded Kaia Kanepi 7-5, 6-2. Kuznetsova was runner-up at Roland Garros to Justine Henin in 2006.
The other semifinal will be an all-Serbian match, with No. 2-seeded Ana Ivanovic playing No. 3 Jelena Jankovic. Ivanovic beat Patty Schnyder 6-3, 6-2 Tuesday, and Jankovic defeated unseeded Carla Suarez Navarro by the same score.
The big-hitting Safina changed tactics when she fell behind in the second set, switching to a less aggressive approach. The strategy coaxed a flurry of errors from an increasingly flustered Dementieva.
"I changed my game completely,'' Safina said. "I think she got confused, because I wasn't hitting the ball anymore like I did in the first set. I was like, `OK, you have to hit winners.'''
Safina won five consecutive games to climb back into the match, and Dementieva had to erase three set points in the next game to hold for 6-all.
In the tiebreaker, Dementieva committed three consecutive unforced errors to fall behind 6-3. On Safina's sixth set point, she skipped a backhand off the baseline for a winner to take the 80-minute set and even the match.
It was then a sprint to the finish. A dejected Dementieva gave away the final set, committing 15 unforced errors while winning only 14 points.
Kanepi, an Estonian playing in her first Grand Slam quarterfinal, was hurt by her own mistakes, too. She committed 31 unforced errors and lost 16 of 24 points on her second serve.
Still, Kanepi took an early lead.
"She started very well. She was hitting so hard,'' Kuznetsova said. "I showed her that I was tough, and so at some moments she started to miss more.''
Kuznetsova lost serve to fall behind 4-2 when she ended an 11-stroke exchange by putting a forehand into the net. Kanepi raised a fist, bent over and yelled in excitement, while her supporters in the guest box stood and cheered while waving Estonian flags.
Kanepi went ahead 40-love in the next game, a point from a 5-2 lead, before her game unraveled. Kuznetsova won the next point, a 12-stroke rally, with a forehand winner, and Kanepi dropped the next four points too, all on her miscues, capped by a double-fault on break point.
That began a run in which Kuznetsova won five of six games - and 23 of 32 points - to take the first set.
She raced to a 5-1 lead in the second set, and after closing out the victory with a forehand winner, she waved a clenched fist as she walked to the net.
Three-time defending champion Rafael Nadal was toasted on his 22th birthday Tuesday after he gave himself another berth in the semifinals. He drubbed fellow Spaniard Nicolas Almagro 6-1, 6-1, 6-1, the most lopsided victory by Nadal in two days.
On Sunday, he routed yet another poor Spaniard, Fernando Verdasco, 6-1, 6-0, 6-2.
"I play better and better every match,'' Nadal said. The going's about to get tougher. A potential final looms against No. 1-ranked Roger Federer, but first No. 2 Nadal must beat No. 3 Novak Djokovic on Friday in a semifinal widely anticipated since the draw was held nearly two weeks ago.
In the last quarterfinal matches Wednesday, Federer was to face No. 24 Fernando Gonzalez, and No. 5 David Ferrer was to meet unseeded Gael Monfils, the only French player remaining.
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Safina beats Dementieva to win German Open
