By Julien Pretot
NEW YORK (Reuters) - Petra Kvitova signaled her return to top form eight months after sustaining a career-threatening hand injury with an impressive 7-6(3) 6-3 win over pre-tournament favorite Garbine Muguruza to reach the U.S. Open quarter-finals on Sunday.
The Czech was sidelined for five months after being stabbed in her left playing hand by an intruder at her home and although the 13th seed has gradually moved towards her best level, Muguruza was the hot favorite under the lights at Arthur Ashe Stadium.
"I tried to work really hard to play here again. It means a lot, it's an incredible night to play in front of a great crowd," Kvitova said in her on-court interview.
"I don't think I can find the right words, it was a difficult time, all five months (away) were very tough.
"It was a tough journey that I didn't know how would end.
"Everything after what happened is something new and I really appreciate every experience that I have right now in life. Every moment I am living now is something really special."
The Spanish third seed Muguruza had only dropped nine games en route to the fourth round and her poise, pace and power helped her quickly open a 4-1 lead.
Kvitova then staved off a break point and it jump-started her game.
"Even though I was winning 4-1, I think she was playing great. Looking at her past matches, I think she was playing even better," said Muguruza.
"So I felt like she was superior today. You know, great for her. She played very good."
Targeting her opponent's misfiring forehand, Kvitova leveled to 4-4 and had break points at 5-4 and 6-5 before sealing the tiebreak.
The twice Wimbledon champion, who will next face local favorite Venus Williams, the ninth seed, stayed composed while Muguruza grew increasingly nervous, challenging line calls with no apparent reason as Kvitova moved her left and right with her crafty left hand.
Muguruza seemed back on track in the second set when she broke in the first game but Kvitova grabbed it back and cantered to a 4-1 lead as the Spaniard was given a warning for coaching.
Muguruza hung in by her teeth but she wasted three chances to break back in the ninth game before Kvitova prevailed on her second match point when the Spaniard sent a forehand long.
(Reporting by Julien Pretot; Editing by Ian Ransom/Sudipto Ganguly)