LONDON - Kirsten Flipkens and Sabine Lisicki, whose careers were almost wrecked by illness and injury, booked emotional places in the Wimbledon semi-finals Tuesday.

Flipkens will be playing in her first Grand Slam semi-final at the age of 27 after knocking out 2011 champion Petra Kvitova, 4-6, 6-3, 6-4, The Belgian 20th seed goes on to face 2007 runner-up Marion Bartoli, the 15th seed, who defied a chorus of boos before seeing off American 17th seed Sloane Stephens, 6-4, 7-5. Lisicki made her second Wimbledon semi-final by cruising past Kaia Kanepi of Estonia, 6-3, 6-3.

The German 23rd seed now tackles Polish fourth seed Agnieszka Radwanska who battled past Chinese sixth seed Li Na, 7-6 (7/5), 4-6, 6-2. This time last year, Flipkens, the 2003 junior champion, was ranked a lowly 262 in the world after blood clots in her left ankle forced her to take several months off. "It's amazing, it's more than a dream come true to be in the semi-final of a Grand Slam, it's ridiculous," Flipkens said. "Last year I didn't even get into the qualifying of Wimbledon. I still cannot believe it. I was so calm on the court, I had nothing to lose and I just went for my shots." Lisicki followed-up her shock defeat of five-time champion Serena Williams to book her place in her second Wimbledon semi-final. The German also made the last-four as a wildcard in 2011, three months after her world ranking had slumped to 218 as she fought her way back from a serious ankle injury which left her "needing to learn to walk again".

"It was an amazing match yesterday, but I had to make sure that I had calmed down and was ready for today," said Lisicki, who completed victory in her fourth Wimbledon quarter-final just before rain began to fall. "I have had experience of other years to help me. I also played the semi-finals in 2011 so that helped me be ready for today." Lisicki, who was defeated by Maria Sharapova in the semi-finals two years ago, insisted that she felt no pressure coming into Tuesday's match having downed Williams in the fourth round. "There's no pressure. I just keep playing the game that I love," she added. It's also a surface she loves -- the German's record at Wimbledon stands at 18 wins and just four losses while she is only 16-15 at the three other Slams. Kanepi has now played and lost six quarter-finals at the majors. Radwanska, the highest seed left following the exit of defending champion Williams, Victoria Azarenka and Sharapova, beat Li in a gripping two-hour, 43 minute contest which was completed under the Centre Court roof. Radwanska, the runner-up in 2012, took victory on an eighth match point.

The 24-year-old Pole, who had gone into the quarter-final with a 4-6 losing record against Li, also overcame an injury scare when she needed her right thigh tightly-strapped at the start of the deciding set. "Li played unbelievable tennis. I was just happy to get through after struggling in the final set," said Radwanska who had also needed three sets to beat Tsvetana Pironkova in the fourth round.

"I have played so much tennis in the last few days, that's why I have the problem." Li fired 58 winners in Tuesday's quarter-final but was undone by 40 unforced errors. Bartoli, the 2007 runner-up to Venus Williams, fell foul of the fans on Court One when she demanded that play be stopped when she was leading 5-4, 40-40 with Stephens serving as light rain began to fall.

When they resumed after two and a half hours, Stephens quickly dropped the first set and slipped 2-0 down in the second, losing the first nine points as the crowd, convinced that the Frenchwoman's complaints over the state of the court had been unjustified, jeered following their lengthy wait. "I don't get why the crowd was against me," said the 28-year-old Bartoli.

Meanwhile, Novak Djokovic and Andy Murray edged closer to an epic Wimbledon final showdown on Monday while Poland played Grand Slam gatecrashers by guaranteeing at least a semi-final spot. World number one Djokovic, the 2011 champion, dropped his serve for the first time at this year's tournament before beating Tommy Haas, the 35-year-old German 13th seed, 6-1, 6-4, 7-6 (7/4) in the fourth round. Djokovic will be playing in his 17th successive Grand Slam quarter-final where he will face Tomas Berdych, the seventh seed and 2010 runner-up, who beat Australia's Bernard Tomic, 7-6 (7/4), 6-7 (5/7), 6-4, 6-4. Djokovic boasts a 13-2 career record over Berdych but lost to him at Wimbledon in 2010.

"Haas is always a tough opponent. I had lost to him twice on grass before. He has great variety in his game and I always knew it would be a tough challenge," said Djokovic, who fired 13 aces and 40 winners. "It was never going to be easy. I had to work for my games but I served well and returned well. I am happy to have closed it out in straight sets. "I am playing really good tennis now, maybe even better than when I won the title in 2011."

Second seed Murray took another step closer to ending Britain's agonising 77-year wait for a men's champion when he survived a second set wobble to carve out a 6-4, 7-6 (7/5), 6-1 win over Russian 20th seed Mikhail Youzhny. Murray, the runner-up to Roger Federer in 2012, will face Spain's Fernando Verdasco for a place in the semi-finals. The Scot has an 8-1 winning record over unseeded Verdasco, a former top-10 player. Murray had to battle back from 2-5 down in the second set to quell the threat posed by Youzhny, who needed treatment on a shoulder injury after one game of the third set. Murray put in an impressive serving performance, firing 15 aces and hitting 45 winners past the experienced Russian.

"Roger's lost and Rafa's lost. All these guys are better players than me and have achieved a lot more than me and so if they can lose so can I. I just concentrate on the next one and try and get through it," he said. Verdasco, a former world number nine who now stands at 54 in the world and is playing his 41st successive major, reached his first Wimbledon quarter-final with a 6-4, 6-4, 6-4 win over unseeded Frenchman Kenny De Schepper.

Davis Cup teammates Jerzy Janowicz and Lukasz Kubot set-up the first ever all-Polish quarter-final. Janowicz, the 24th seed, defeated Austria's Jurgen Melzer, 3-6, 7-6 (7/1), 6-4, 4-6, 6-4 on the back of 16 aces and 34 winners as he reached his first Grand Slam quarter-final.

 The 22-year-old was joined in the last eight just moments later by 31-year-old Kubot, the lowest-ranked player left at 130 in the world, who defeated France's 111th-ranked Adrian Mannarino, 4-6, 6-3, 3-6, 6-3, 6-4.

The last Pole to reach the last-eight at Wimbledon was Wojtek Fibak in 1980. "It's unbelievable what is going on right now. We have two players in the quarter-finals and a woman in the quarter-finals. I think this is by far the best that possibly could happen to Polish tennis," said Janowicz. Spanish fourth seed David Ferrer reached the quarter-finals for the second successive year by firing 53 winners in his 6-7 (6/8), 7-6 (7/3), 6-1, 6-1 win over Croatia's unseeded Ivan Dodig.

He goes on to tackle Argentine eighth seed Juan Martin del Potro who reached his first Wimbledon quarter-final with a 6-4, 7-6 (7/2), 6-3 win over Andreas Seppi, the 23rd seeded Italian. Del Potro, the 2009 US Open champion, admitted that he is still being bothered by knee trouble. "It bothers me a lot. I couldn't extend 100 percent the knee. The tapes for today helped me to be careful in some movements. But it is not enough," said Del Potro. The 31-year-old Ferrer, who was defeated in the French Open final by Nadal last month, will be playing in his seventh consecutive Grand Slam quarter-final.