The second-seeded Kerber was never more on the brink of defeat than in her quarterfinal against fellow German Mona Barthel. In fact, she was down 5-2 in the third set, and at 5-4 on her own serve survived two match points before eventually prevailing, 62 06 75.
"It was a very tough match. Mona played unbelievable tennis, especially in the second, where I actually had no chance," said Kerber, who fell to Barthel in their only previous meeting in the semifinals of Hobart in January. "I'm tired physically, but it was even tougher mentally, because it went back and forth. I'm really happy that I could get back from 5-2 down in the third."
Kerber has now made at least the final four in five of her eight WTA events this year, with semifinal showings at Auckland, Hobart and Indian Wells, her first career title at Paris [Indoors] and at least a semifinal showing here.
Awaiting her in the final four is No.3 seed Jelena Jankovic, whom she has never played. The Serb was a 46 61 63 winner over Kaia Kanepi. Jankovic had been on a four match losing streak entering Copenhagen but is now into her third semifinal of the season.
"It was a tough match. I am a bit tired, but I feel good in general," Jankovic said. "She played really well, and I made too many mistakes at some bad times.
"I'm glad I chose to play here for the first time. It is a part of the world where I have never been, so I thought why not?"
Jankovic is not worried about Copenhagen affecting her preparation for Serbia's Fed Cup semifinal in Russia next week.
"I'm not concerned about going from here to Fed Cup on clay," Jankovic said. "I think it is easier to go from hardcourts to clay than the other way around."
The other semifinal will see No.1 seed and two-time-defending champion Caroline Wozniacki take on Petra Martic. Wozniacki raced out to a 60 30 lead en route to beating Alizé Cornet, 60 63, raising her record here to 13-0. Not only that, she has won 19 straight sets in Copenhagen dating back to the 2010 semifinals, her best streak at any event.
"I played well. I got a lot of first serves in and I didn't make any unforced errors, which always helps, of course," said Wozniacki, who takes a 28-11 career semifinal record into Saturday's match. "Maybe I lost a little focus during the second set, but that's not unusual when it goes so smoothly in the first."
As for Martic, she got past Bojana Jovanovski, 64 46 63, to make the semis for the second straight year here. She will have her hands full, though, as she is 0-6 in her career against Top 10 players, including two losses to Wozniacki.
This is the second event this year in which the Top 3 seeds made the semifinals after Acapulco, in which the Top 4 seeds occupied the final four.