LONDON  -  Sabine Lisicki ended Serena Williams’ reign as Wimbledon champion as the German 23rd seed clinched a stunning 6-2, 1-6, 6-4 victory over the world number one in the fourth round on Monday.Lisicki, who plays Estonia’s Kaia Kanepi for a place in the last four, has an impressive Wimbledon record, reaching the quarter-finals three times and the last four in 2011, but this incredible upset on Centre Court was by far her greatest achievement at the All England Club. The 23-year-old has failed to make it past the fourth round in 16 Grand Slam appearances outside Wimbledon, but she comes alive on the grass-courts of south-west London. “I’m still shaking, I’m so happy”, said Lisicki, breaking into tears.“Serena played a fantastic match. She’s such a tough opponent and it’s just an amazing feeling to win. “The crowd was so amazing. I love this court so much, it’s such a special place for me. “I did enjoy it. She played some unbelievable shots. I was just fighting for every single point and hanging in there. Her remarkable victory was no fluke. Despite facing the most ferocious hitter in the history of women’s tennis, Lisicki matched Serena blow for blow, unloading more winners and serving more aces than the five-time Wimbledon champion in two hours and four minutes of high drama.In a tournament most memorable this year for the fall of its biggest stars, this was arguably the most astonishing result of all. Since an embarrassing first round loss against Virginie Razzano at last year’s French Open, Williams had simply been unstoppable, winning 77 of her 80 matches and collecting the Wimbledon, US Open, French Open and Olympic titles in the process. The 31-year-old, a 16-time Grand Slam champion, had swept through the first week, dropping just 11 games in her opening three matches to extend her winning run to 34 matches.But Lisicki’s game is perfectly suited to grass and right from the start it was clear she was capable of upsetting the odds as she earned a break point in the fourth game of the match. Serena saved it, unleashing a shrieked ‘come on’ that suggested she was well aware of the threat. Lisicki wasn’t deterred and she kept the pressure on Williams, earning another break point in the sixth game which she converted when the American blazed a forehand wide.Serena appeared rattled, gesticulating to her French coach Patrick Mouratoglou and swiping at the turf in frustration as Lisicki punished another shaky service game. By the time Lisicki closed out the set, she had won four games in a row. Serena hit back, breaking to love in the third game of the second set during a run of 14 successive points for the American. She took the set with two more breaks and by the time Williams moved into a 3-0 lead in the deciding set she had won nine consecutive games.But Williams’ concentration wavered with the finish line in sight, allowing Lisicki a lifeline as the German broke in the fifth game. Even when Williams’ broke straight back, Lisicki wouldn’t surrender and another break from the German made it 4-4. Incredibly, Lisicki was back on top and she broke for a 5-4 lead when Williams sent a smash just beyond the baseline.Lisicki couldn’t convert her first match point, sending a forehand long. A double-fault then gifted Serena a break-point, but the German saved it with an ace. Another big serve brought Lisicki a second match point and this time she seized her chance, finishing off an epic upset with a flashing winner. Former champion Petra Kvitova booked her fourth consecutive Wimbledon quarter-final appearance with a 7-6 (7/5), 6-3 win over Spain’s Carla Suarez Navarro. Czech eighth seed Kvitova, who won Wimbledon in 2011, overpowered Spanish 19th seed Suarez Navarro with 23 winners and will face Belgian 20th seed Kirsten Flipkens for a place in the semi-finals. As the highest seed remaining in the bottom half of the draw, Kvitova has a golden opportunity to reach her second Grand Slam final. Since her surprise Wimbledon triumph, Kvitova has struggled to fulfil her potential and her last three Grand Slam appearances ended by the fourth round.But she had made at least the last eight in each of her previous three visits to Wimbledon and the 23-year-old had one foot in the quarters again when she won a tight first set tie-break. Kvitova landed the decisive break for a 4-2 lead in the second set before serving out the win. Flipkens sealed her first Grand Slam quarter-final berth with a 7-6 (7/2), 6-3 victory against Italian veteran Flavia Pennetta.The 27-year-old, who had failed to get past the third round in five previous Wimbledon appearances, appeared overwhelmed by her success as she crouched down to kiss the grass before wiping away tears as she waved to the crowd. Also later, unseeded Laura Robson will try to become the first British woman to reach the quarter-finals since Jo Durie in 1984. Australia-born Robson, ranked 38th and the first British woman to reach the last 16 for 15 years, takes on Estonia’s Kaia Kanepi, the world number 48, in the opening match on Court One.  Polish fourth seed Agnieszka Radwanska, last year’s beaten finalist, plays Tsvetana Pironkova, a Bulgarian grass-court specialist who reached the All England Club semi-finals in 2010 and the last eight in 2011. China’s Li Na, seeded sixth and a former French Open champion, faces Italian 11th seed Roberta Vinci. The presence of Williams, Pennetta, Li and Vinci in the fourth round represents the most 30-somethings through to the last 16 of any major since Wimbledon in 1994. French 15th seed Marion Bartoli, the runner-up in 2007, plays Karin Knapp, the Italian world number 104. Puerto Rico’s Monica Puig, the world number 65, will hope to extend her surprise run when she faces American 17th seed Sloane Stephens. Puig, who shocked fifth seed Sara Errani in the first round, is making her grass-court debut as a professional and stands one win away from her maiden Grand Slam quarter-final.