KEY BISCAYNE, Fla. -- Novak Djokovic benefited from an erroneous call and claimed he didnt realize he had broken the rules. When Andy Murray walked to the net and challenged him about it, Djokovic responded with a shrug and a sheepish smile. Murray lost the dispute, and the match. The pivotal ruling against the defending champion helped Djokovic win 7-5, 6-3 in the quarter-finals of the Sony Open. Roger Federer was up a service break twice in the second set but lost to No. 20-seeded Kei Nishikori 3-6, 7-5, 6-4. Nishikori will play Djokovic on Friday. The point that aggravated Murray occurred at the start of the 12th game, when he was serving at 5-6. Djokovic charged forward to volley a short ball and hit it for a winner. Murray argued -- and TV replays confirmed -- he should have been awarded the point because Djokovics racket was on the far side of the net when he hit the ball. Chair umpire Damian Steiner declined to change his call, and such rulings cant be appealed for video review. Murray briefly discussed the matter with Djokovic. "I went and asked Novak, and he told me he was over the net," Murray said. "Look, it might be my mistake," Djokovic said. "I think I crossed the net with the racket. I didnt touch the net. Maybe the rule is that you are not allowed to pass on his side with the racket. Im not sure. You tell me." That is indeed the rule. Djokovic said that if he had understood it correctly, he would have conceded the point. A flustered Murray committed unforced backhand errors on the next three points to lose the game and the set. "Obviously, that distracted him mentally, and after that he gave the set away," Djokovic said. Murray took a lead in the second set but lost the final four games and the last 12 points. Afterward, he downplayed the bad call. "Im not angry," he said. "It maybe had a slight bearing on that game, but I was still up a break in the second set." Nishikori will be playing in only his second ATP Masters 1000 semifinal, and his first in 2 1/2 years. "I thought I really played well, especially in the third set," Nishikori said. "I was hitting balls deep and striking well. Everything was going well." Federer was the runner-up to Djokovic at Indian Wells two weeks ago, and said hes pleased with his start to the year despite the latest loss. "I just couldnt find my rhythm on the serve today, which was surprising," Federer said. "Its a bit frustrating, but Kei did well to stay with me. He was more consistent in the second and third, and in the end its to his credit." Li Na became the first Chinese woman to reach the Key Biscayne semifinals when she beat Caroline Wozniacki 7-5, 7-5. Lis opponent Thursday night will be Dominika Cibulkova, who erased three match points in the second set -- one when a call was overturned via replay -- and beat Agnieszka Radwanska 3-6, 7-6 (5), 6-3. Six-time champion Serena Williams will play five-time runner-up Maria Sharapova in the other womens semifinal. Williams has beaten Sharapova 14 consecutive times. Murray won the Key Biscayne title in 2009 and 2013 but wasnt at his best against Djokovic. The Scotsman committed five double-faults and 32 unforced errors, including a flurry down the stretch. He took a 3-2 lead in the second set with his only service break, then double-faulted twice to give it right back. But it all might have been different if not for the call that made one point stand out from the other 125. Djokovic had won praise for his sportsmanship when he conceded a point following an erroneous call in his match Tuesday, but against good friend Murray, he left the verdict to the umpire. A sideline reporter told Murray that TV replays showed he was correct about the call, and during the ensuing changeover he questioned Steiner. "His racket was over the net," Murray said. "Its quite clear. You can see it on the replay." "I have to make a decision at the moment," Steiner replied. Any hard feelings on Murrays part didnt carry over after the match, when he shook hands with Djokovic and Steiner. "Its a hard one for the umpire to call," Murray said. "Just frustrating." And Djokovic said the call was the umpires to make. "Its not my fault," he said. "I mean, I was never lying on the court. I always try to be fair to whoever I play against." Tony Romo Womens Jersey . The Vancouver coach and an announced sellout crowd of 18,910 watched in dismay as the Canucks lost 7-4 to the New York Islanders on Monday night by squandering a 3-0 lead in the third period. Tony Pollard Jersey . However, it wasnt a problem on Monday night. Evgeni Nabokov made 23 saves for his 56th career shutout in the New York Islanders 3-0 win over the Detroit Red Wings on Monday night. http://www.shoptheofficialcowboys.com/Elite-Bill-Bates-Cowboys-Jersey/ . He says he will have the operation Wednesday and be ready in time for training camp in September. Bernier missed five games in March due to the injury. Emmitt Smith Jersey .Hammel pitched inside more and it helped him get into the seventh inning as the Colorado Rockies beat the San Diego Padres 3-2 on Friday night. Chuck Howley Youth Jersey . -- The San Francisco 49ers have re-signed cornerback Perrish Cox to a one-year contract.Tony Stewart could still face criminal charges for running down Kevin Ward Jr. with his sprint car, even if the three-time NASCAR champion didnt mean to kill Ward, hurt him or even scare him. Ontario County Sheriff Philip Povero, who announced on Tuesday that the investigation is continuing, has said that his initial findings have turned up nothing that would indicate criminal intent in the crash at the Canandaigua Motorsports Park. But legal experts agree that does not mean Stewart is in the clear. The NASCAR star could be charged with second-degree manslaughter under New York law if prosecutors believe he "recklessly caused the death of another person," with negligent homicide another possibility, according to criminal law professor Corey Rayburn Yung of the Kansas University School of Law. "The question over whether someone was reckless is a factual one, and one a prosecutor might let a jury decide," said Yung, who also posts at the Concurring Opinion blog. Athletes in competition often do things that would get the average person arrested -- think two boxers in the ring, or a baserunner sliding into second with his spikes high. But sometimes an act is so far outside the bounds of accepted sporting behaviour that it becomes a crime, as former major leaguer Jose Offerman learned when he was charged with felony assault for rushing the mound -- swinging a bat -- after he was hit by a pitch in a minor league game. So Stewart would not expect to be charged for the car-on-car bump that sent Ward spinning into the wall. But if, for example, he were to tell police that he saw Ward on the track and tried to shower him with dirt or otherwise send him a message, a first-degree manslaughter charge could be a possibility, Yung said. In a 1949 case that Yung uses in his class, midget car racer Joseph Sostilio was found guilty of manslaughter after he tried to squeeze a four foot-wide vehicle through a two-foot opening at 40 mph, crashing into another car and sending it into the one driven by Stephen D. Bishop. Bishops car flipped three times and he was killed. Sostilios conviction was upheld on appeal by the Massachusetts Supreme Judicial Court. Noting that a violent or aggressive act on a football field or in a boxing ring is not necessarily a crime, Justice Henry Tilton Lummus wrote: "In the present case physical contact was not an essential part of the racing of automobiles." That was a half-century ago, and racing has changed.dddddddddddd Trading paint is a part of the sport, and its not even uncommon these days for racers to leave their cars to confront rivals after a crash, which Ward appeared to be doing when he was killed. "In sports we tend to allow all sorts of conduct wed never allow in another circumstance," Yung said. "But this isnt a collision. Its not in that ballpark; its something you dont expect. This is a more complicated scenario. Were assuming Stewart didnt mean to do this, and yet a death resulted." Whether Stewarts actions were part of racing depends on what the police investigation finds. Unlike the cars Stewart drives on the NASCAR circuit, the sprint cars have no radios or instrument data recorders that could tell authorities exactly what was happening when Stewart hit Ward. Povero would not say how Stewart described the accident, but he said Monday he has reviewed two videos and spoken to Stewart. "The worst thing that could happen for Stewart is if his story doesnt seem to match other evidence," Yung said. "Because then it might call into question his own story." Poveros previous comments that he found no criminal intent all but rules out the possibility of a first-degree murder charge, which would essentially require a confession that Stewart was trying to kill Ward. For second-degree murder, prosecutors would need to prove Stewart was reckless in combination with a "depraved indifference to human life." "Mr. Stewart has fully co-operated with the police officers that are investigating," Povero said in a news conference shortly after the race. "He was visibly shaken by this incident, and has promised his continuing co-operation in this investigation." After the investigation is completed, Povero said, the evidence will be turned over to the district attorney as a matter of routine. Even if he is cleared by prosecutors, though, Stewart could face a civil suit. Although the standard of proof is lower than in a criminal case, the civil court would also consider Wards state of mind at the time of the accident and whether he was also negligent in venturing into racing traffic on a dark track in a dark suit. But Stewart would also have to weigh the damage to his image and career -- with his own team, tracks and millions in endorsements -- making a quick settlement likely. ' ' '