Petra Kvitova is back in the semis (STEFAN WERMUTH / REUTERS)

Petra Kvitova lost her concentration in the second set against Tsvetana Pironkova — and nearly lost her quarterfinal Wimbledon match.

She regained her bearings in time, though, to win 6-3, 6-7 (5-7), 6-2 and reach the semifinals of the tournament for the second straight year.

Kvitova, the eighth seed from the Czech Republic, dropped the second set when she squandered a 4-1 lead in the tiebreak.

“I am so happy to be in the semifinal,” Kvitova said. “I made some mistakes in the second set and was a bit down mentally.”

“It’s great to be back in the semifinal and now I have more experience of the Centre Court.”

Kvitova, a 21-year-old lefthander, will play Victoria Azarenka, who beat Tamira Paszek, for a place in the final. That match was played with the Centre Court roof closed because of rain. The roof has been closed 12 times so far this year; it was closed only three times the last two years.

Maria Sharapova will play Sabine Lisicki in the other semifinal Thursday.