LONDON (AP) Two-time champion Petra Kvitova made a stunning first-round exit from Wimbledon on Tuesday as she lost 6-4, 4-6, 6-0 to unseeded Aliaksandra Sasnovich of Belarus.
The eighth-seeded Kvitova entered the tournament as one of the favorites despite having withdrawn ahead of the third round at Eastbourne last week with a right hamstring complaint.
However, that didn't appear to be affecting her as she rallied to level the match by winning the second of two closely fought sets.
Despite the 2011 and 2014 Wimbledon champion being vastly more experienced than Sasnovich - who has never been beyond the third round at a Grand Slam - Kvitova was the one overcome by nerves in the deciding set.
''The nerves were there again,'' Kvitova said. ''I just tried to kind of fight with myself.''
As Kvitova faltered, the other major contenders on her side of the women's draw advanced in style.
After losing just one set on her way to the Wimbledon title a year ago, Garbine Muguruza picked up exactly where she left off, beating British wild card Naomi Broady 6-2, 7-5 on Tuesday.
The No. 3-seeded Muguruza saved the only break point she faced and could have ended the encounter more swiftly had she taken advantage of her own chances.
''I'm pretty happy with my serve and controlling the emotions,'' Muguruza said. ''You know, to be back in a Grand Slam is always difficult, so I'm excited with the way I'm playing.''
The usual adulation afforded to the reigning champion fulfilling the honor of opening proceedings on Centre Court on Day 2 of the tournament was tempered by the nationality of Muguruza's opponent. Muguruza was shown respect but the British crowd backed Broady.
However, the 2016 French Open champion quickly dispelled any thoughts of an upset by breaking Broady's opening service game, and did it again to take the first set 6-2.
Broady saved six break points in the second set before succumbing to Muguruza's constant pressure in the 12th game.
Muguruza had no complaints.
''I found the crowd very fair, with both of us,'' she said.
The Spaniard failed to build upon her dominant display at last year's Wimbledon as she exited the U.S. Open in the second round and this year's Australian Open in the fourth.
However, her best tennis - and both of her Grand Slam titles - have come during the European summer, and a run to the French Open semifinals last month suggests that may be the case once more.
Only an inspired performance from eventual champion Simona Halep knocked her out at Roland Garros, and with grass being better suited to Muguruza, she is a major contender at Wimbledon.
''The fact that it's different surfaces, it helps,'' Muguruza said.
Her next opponent will be unseeded Belgian Alison Van Uytvanck.
The top-seeded Halep, playing her first match since winning the French Open, recorded a comfortable 6-2, 6-4 win over Japan's Kurumi Nara.
Johanna Konta, who knocked out Halep on the way to the semifinals a year ago, made it through to the second round by defeating Natalia Vikhlyantseva of Russia 7-5, 7-6 (7).
Australian trio Daria Gavrilova, Ashleigh Barty, and Samantha Stosur all advanced with straightforward wins.
The 26th-seeded Gavrilova cruised past U.S. lucky loser Caroline Dolehide 6-2, 6-3. She will face Stosur in the next round, after the 2011 U.S. Open champion defeated Shuai Peng of China 6-4, 7-5.
Meanwhile, the 17th-seeded Barty defeated Swiss opponent Stefanie Voegele 7-5, 6-3 to claim her first main-draw singles victory at the All England Club. She will next face British wild card Gabriella Taylor or 2014 runner-up Eugenie Bouchard.
There were also surprise defeats on the men's side of the draw as both David Goffin and Dominic Thiem lost.
The 51st-ranked Matthew Ebden upset 10th-seeded Goffin of Belgium 6-4, 6-3, 6-4, before seventh-seeded Thiem retired hurt with his opponent, Marcos Baghdatis, leading 6-4, 7-5, 2-0.
Two-time champion Rafael Nadal moved into the second round with a 6-3, 6-3, 6-2 win over Dudi Sela of Israel.
The second-seeded Nadal hadn't played a match since claiming his 11th French Open title last month, but showed little sign of rust as he cruised to victory against Sela.
Juan Martin del Potro improved to 9-0 in the first round of Wimbledon with a 6-3, 6-4, 6-3 win over Peter Gojowczyk of Germany.
The fifth-seeded Argentine will next face Feliciano Lopez, who broke Roger Federer's record by appearing in a 66th consecutive Grand Slam singles tournament as he defeated Federico Delbonis of Argentina 6-3, 6-4, 6-2.
Fourth-seeded Alexander Zverev was also through after defeating James Duckworth of Australia 7-5, 6-2, 6-0.