'Miracle worker' Kvitova returns to Roland Garros quarter-finals

An emotional Petra Kvitova hailed her first appearance in the French Open quarter-finals since 2012 on Monday as a welcome reminder of the two-time Wimbledon champion's ability on all surfaces.

The Czech seventh seed cruised into the last eight at Roland Garros for just the second time in her career with a 6-2, 6-4 win over China's Zhang Shuai.

"After eight years to be in the quarter-final again, it's great. I'm really happy for that, that I'm still able to play on all surfaces," said Kvitova.

Her best run in Paris came when she lost to eventual champion Maria Sharapova in the semi-finals in 2012.

"I think I wasn't really the player who ever succeeded on the clay. At that time was such a great thing for me to be in the semi-finals. 

"I've been playing really good. I think it's been a miracle for me to make the semi-final here in Roland Garros."

Kvitova, who missed last year's tournament due to an arm injury, will play German veteran Laura Siegemund for a place in the last four.

"I got a bit emotional last two points of my match. I really started to think still about the match because in tennis we really never know when it's the end," she said.

Court Philippe Chatrier holds special memories for Kvitova, as the site of her comeback in 2017 six months after a knife attack that almost ended her career.

Kvitova, now 30, suffered serious injuries to her left playing hand when she fought off a knife-wielding burglar at her home in Prostejov in December 2016.

"Happy memories, when I made my comeback here 2017, when I step on the Philippe Chatrier, I couldn't really imagine me to be in the quarter-final of this Slam," she said.

"Everything just came back to me. When I'm talking, I'm getting emotional again. It's been a long ride definitely. Everything came to my mind when I had my whole family, people who I loved to helped me through the tough, tough time." 

Kvitova, a runner-up to Naomi Osaka at last year's Australian Open, has won the majority of her 27 titles on hard courts but is a capable clay performer as well.

She has won five of her six finals on the surface, with three of her past five titles coming on clay including the most recent at Stuttgart last year.

"One year I do remember I won tournaments on all surfaces. I showed myself that I can really play on every surface," said Kvitova, who will climb back into the top 10 following her performance in Paris.

"When the roof is closed (on Chatrier) it's like being indoors and I really love to play."