Prague: Two-time Wimbledon champion Petra Kvitova will be out of the sport for six months while her playing hand, wounded in a knife attack, recovers its strength, the surgeon who operated on her said on Wednesday.

Kvitova was injured on Tuesday when she fought off an intruder in her apartment in the Czech Republic.

"When we talk about (competitive) pressure on the hand, we are talking about a period of six months (before that is possible)," Radek Kebrle said in a televised news conference.

"She is a young athlete, healthy... But it still is a relatively massive injury," he said, adding that all the fingers on Kvitova's left hand were hurt as she grabbed the attacker's knife.

Her spokesman, Karel Tejkal, earlier described Tuesday's near four-hour operation as a success and said Kvitova's mood was optimistic.

But both he and the Women's Tennis Association suggested her future in the sport was uncertain.

"There will be several weeks of waiting with a splint and then, gradually, slowly she will be able to put the hand to work," Tejkal told Czech public television.

But any return to competitive tennis for the Czech world No. 11 was "weeks and months" away, he said.

The WTA, the umbrella organisation for the women's professional game, said it regretted her absence from the circuit.

"It's unclear if or when Kvitova will be back on the court, and the start of 2017 won't be the same without her unique power and competitive spirit," the association said on its website .

Earlier in the day, Tejkal said: "Petra is feeling good after the surgery, a routine check confirmed that the operation was successful."

Kvitova had said on social media before undergoing surgery that the attack had left her "shaken, but fortunate to be alive".

The assault took place in her flat in the city of Prostejov, about 260 km (160 miles) southeast of Prague, the location of a tennis club where she, men's world No.10 Tomas Berdych and other top-ranked Czech players often train.

Czech media reported the intruder presented himself to Kvitova as a boiler inspector.

"In my attempt to defend myself, I was badly injured on my left hand," Kvitova said on Twitter. "The injury is severe and I will need to see specialists, but if you know anything about me I am strong and I will fight this."

The 26-year-old had been due later in the day to play a charity event in the Czech Republic's second biggest city Brno alongside compatriot Lucie Safarova. The pair have been fixtures in the Czech Fed Cup team that has won the premier women's team tennis event in five of the last six years.

"What happened to Petra, can happen to any of us. I got goosebumps from it," Safarova told news website Aktualne.cz.

The hard-hitting left-hander rose to No.2 in 2011 when she won the first of her two Wimbledon singles titles.

The 26-year-old slipped in the rankings this year but showed improved form in recent months, winning the Wuhan Open title in October and the season-ending WTA Elite trophy in November.