PARIS (AP) — There are at least two things that haven't changed during Petra Kvitova's six-month layoff. She remains a fierce competitor, and she still has her sense of humor.

The two-time Wimbledon champion's comeback ended in the second round of the French Open on Wednesday after a close match against qualifier Bethanie Mattek-Sands, who recorded her best result at a major in nearly two years with a 7-6 (5), 7-6 (5) victory.

Kvitova, who was playing in her first tournament since she was injured in a knife attack at her home in December, threw her racket in frustration after she double-faulted on match point.

"I was mad," Kvitova said.

A reporter then told the Czech player that her racket throwing might be a sign that she is already capable of tapping into her competitive instincts.

"I'm not sure. My father did not like it that I throw my racket, I think," Kvitova replied.

Kvitova had missed all season prior to the French Open while recovering from surgery on her racket-holding left hand. She sustained damage to the tendons, along with injuries to all five fingers and two nerves, during the attack.

Doctors initially thought she would need more time before returning to tennis. But Kvitova's recovery was faster than expected and she signed up for the French Open at the last minute.

In Paris, she managed to win her opening match but the gritty and experienced Mattek-Sands was too much of a hurdle.

"It's weird. I mean, I'm disappointed, for sure. I came here to win the matches," Kvitova said. "The fairytale ended. Now, in upcoming weeks, I think it will be business as usual. That's what I'm looking forward to, just focusing on the tennis and on the game and everything what I do need to improve to my game."

Kvitova will now quickly turn her focus to Wimbledon, where she won the title in 2011 and 2014, and hopes she will be able to play with less media pressure.

"Wimbledon should be much more relaxed afterwards," she said. "I really am looking forward to being there. It's a really great tournament for me. I have the best memories which I can have. I think that my game still suits on the grass, and I will do my best to be there."

Mattek-Sands, a doubles champion at Roland Garros two years ago, is back in the third round of the French Open for the first time since 2013 and will next face Samantha Stosur.

The American with a punk rocker style — she plays in a shirt covered with cherries and wears long black socks — hadn't won a main draw match in the last five Grand Slam tournaments.