(CNN) -- Petra Kvitova says her perspective on life has changed since the knife attack that threatened to cut her tennis career short.

The two-time Wimbledon champion had her left hand slashed after an intruder broke into her apartment in December last year.

Kvitova underwent an emergency four-hour operation to repair damage to tendons and nerves in her left, playing hand and has since been undergoing rehab.

The Czech star still has no date for her return to the sport but says her motivation to get back on the court is huge.

In a post on Instagram she said: "I wanted to say hello since time is flying by -- three whole months already since the attack -- and let you know that I'm working really hard on my recovery.

"I still can't tell you when I will be back, but I can tell you that tennis is a huge motivation for me and I realized while I've been away how much I like challenges!

"My perspective on life has changed a lot and I am doing everything to give myself a second chance to be back on the court. I thank you for staying with me through this."

Kvitova's last appearance was in a Fed Cup tie for her native Czech Republic in the final against France on November 12 last year.

The intruder broke into her apartment in the city of Prostejov, about 160 miles east of the capital Prague, at around 08:30 on the morning of December 20 in an apparent robbery.

After fending him off, Kvitova said she was "shaken, but fortunate to be alive."

She has recently been fitness training in the Canary Islands but speaking to news agency AFP, her spokesman, Karel Tejkal said "everything is up in the air as to her return."

"Petra uses her hand without problem for daily activities. Of course, the hand is weakened but at first glance you can't see that she was injured," he added.

"But at the moment no-one can give a concrete date."

The 27-year-old won both her major titles on grass at Wimbledon, in 2011 and 2014, and reached a career-high ranking of world number two in October 2011.