PRAGUE (AP) — Petra Kvitova could return to tennis in about six months, the surgeon who operated on the two-time Wimbledon champion's left hand said Wednesday.

Kvitova was injured Tuesday when a knife-wielding intruder attacked her at her home in the town of Prostejov. The attacker is still at large and police have asked the public for help.

Kvitova underwent nearly four hours of surgery on Tuesday at a specialized clinic in the northern town of Vysoke nad Jizerou.

"When we talk about (playing tennis), it will take about six months," said surgeon Radek Kebrle of the Hand and Plastic Surgery Institute. "It's a serious injury and we have to deal with that accordingly.

"She's young and healthy and has long, slim fingers," he said. "That's a good prognosis."

Earlier Wednesday, Kvitova's spokesman, Karel Tejkal, said the surgery was successful and the Czech player was feeling good.

Kvitova sustained damage to the tendons in her left hand, along with injuries to all five fingers and two nerves.

She was taken to the clinic in Vysoke nad Jizerou, an elite institution in the country, after initial treatment at a hospital in Prostejov. Doctors decided to operate on her hand immediately.

Shortly after the attack, Kvitova wrote on Twitter that she expected to recover and get back to playing tennis, saying "if you know anything about me I am strong and I will fight this."

Kvitova won the Wimbledon title in 2011 and 2014. She reached a career-high ranking of No. 2 in 2011, but finished the 2016 season as No. 11.

In April 1993, Monica Seles was at the height of her success when she was stabbed in the back during a changeover at a tournament in Hamburg. A man reached over a courtside railing and knifed her, leaving an inch-deep slit between her shoulder blades.

Seles returned to the game 27 months later and reached the 1995 U.S. Open final.