Novak Djokovic of Serbia reacts after beating Tomas Berdych of the Czech Republic in a Men's singles quarterfinal match at the All England Lawn Tennis Championships in Wimbledon, London, Wednesday, July 3, 2013. (AP Photo/Sang Tan) Andy Murray of Britain arrives for a practice session ahead of his Men's singles semifinal match on Friday at the All England Lawn Tennis Championships in Wimbledon, London, Thursday, July 4, 2013. Jerzy Janowicz of Poland reacts after winning against Lukasz Kubot of Poland in their Men's singles quarterfinal match at the All England Lawn Tennis Championships in Wimbledon, London, Wednesday, July 3, 2013. LONDON (AP) - One semifinalist is rebounding from a taxing five-set comeback. Another was so overwhelmed to reach the final four, he sat on the court and wept. One more has a knee that's being kept in action through the miracles of ice baths, athletic tape and painkillers. And then there's Novak Djokovic. Of the four men preparing for Friday's semifinals at Wimbledon, nobody has had skated through a less-taxing road than the top-ranked and top-seeded Serb, who remains the odds-on favorite to win his seventh Grand Slam title. "Coming into the semifinals, I feel physically fresh," said Djokovic, who has won all 15 sets he's played and averaged less than two hours per match, the lowest total of any of the final four. And I'm ready. Plenty of motivation to win every match that I play here. Djokovic will play eighth-seeded Juan Martin del Potro, who also hasn't dropped a set in his first five matches at Wimbledon, but is the opposite of "fresh" - dealing with the effects of hyperextending his left knee twice: First in a match last Saturday, then again in his quarterfinal victory over David Ferrer. The other men's semifinal pits No. 24 Jerzy Janowicz, a 22-year-old from Poland who is making his deepest run at a Grand Slam, against No. 2 Andy Murray, who came back from two sets down to beat Fernando Verdasco and advance to his fifth straight Wimbledon semifinal. Murray got himself into quite a bind in the Verdasco match, but slowed things down to make a meticulous comeback. He was on the court for 3 hours, 27 minutes to bring his total to 11 hours, 59 minutes, the most of the four semifinalists. How big a toll will all that take? "You never know," Murray said. The next match will be different from the one today. Some of the guys, like Novak, (haven't) lost a set yet. I'm sure he's pretty happy with where his game is at just now. I'm happy to be in the semis. Regardless of whether it's been five sets or the first matches were in three sets, it makes no difference. Murray is trying to reach the final in the fourth straight Grand Slam he's played. He missed this year's French Open with a back injury. He carries the hopes of a nation with him every time he steps on the court at Wimbledon. No British man has won the country's Grand Slam since Fred Perry in 1936. Janowicz is well aware of that. "I hope Andy will feel some kind of pressure," he said. I'm sure he'll feel some kind of pressure because Great Britain is waiting for the (British) champion in Wimbledon. Janowicz knows all about the feeling of playing for a country. In an all-Polish quarterfinal, he defeated Lukasz Kubot in a match he called "one of the toughest matches of my life." I was never in a quarterfinal before. I never had a chance to be in the semifinal of a Grand Slam. I never played against Lukasz before," Janowicz said in describing the emotions of the match. When it was over, he traded shirts with Kubot, soccer-style, then sat in his chair and wept. "You are practicing and working for that kind of moment," Janowicz said. So in my case, it's not easy for me to control these emotions. On Friday, he will be the "other" player in the match against Murray on Centre Court. But Janowicz does have this: a win over Murray last year in Paris, where he made a run to the final that catapulted him more than 200 spots in the rankings to the top 25. "Definitely not an easy match," Janowicz said. What can I say? We'll see. I was able to win one match against him last year, so I hope I'm going to be able to do it one more time. Del Potro's issues are more physical than emotional. When he hyperextended his knee and crumpled to the ground on the fifth point of his match against Ferrer, it looked as if he wasn't going to get back up. After a visit from the trainer, he did. But after advancing to his first Grand Slam semifinal since 2009, when he won the U.S. Open, del Potro conceded there was work to be done to get the knee ready for another match. "I will need to be 100 percent or 110 percent against him," del Potro said. He's the No. He's a former champion here. It's going to be more difficult match for me like today. But if I'm OK, if I do everything good to be ready for my next match, I will be excited to play against him. Djokovic leads their series 8-3. But their last meeting at the All England Club came last year in the bronze-medal match of the Olympics, with del Potro winning 7-5, 6-4. Del Potro also won the last time they played, at Indian Wells this year. On the other hand, Djokovic has won all three matches they've played in Grand Slams, most recently at last year's U.S. Open. I have a great respect for him. He's a Grand Slam winner," Djokovic said. He struggled with injuries in last few years, but every time he comes back he comes back very strong because he just has this talent.