Spain's David Ferrer brings down Novak Djokovic in World Tour Finals

David Ferrer, having seen off Andy Murray in straight sets on Monday afternoon, did the same to the world No1 Novak Djokovic in the ATP World Tour Finals on Wednesday night, and follows Roger Federer into the semi‑finals of this most turbulent of season-ending tournament. Djokovic described his fifth defeat of the year as "the worst". He paid tribute to Ferrer, but said: "Maybe it's because of the length of the season, maybe it's just because I'm not feeling well." Federer is the fittest and best player left in the field. History revisited. The sponsor, Barclays, might have mixed feelings but the fans who have packed out the O2 Arena at every session of the ATP World Tour Finals are loving it, regardless of allegiance. This is tennis – top-level sport, in fact – as it should be, full of uncertainties and edge, with grit beating genius, tired muscles succumbing to the commitment of the underdog. The Spaniard, ludicrously ignored in most discussions despite his No5 world ranking, beat Djokovic convincingly 6-3, 6-1 in an hour and a quarter, stunning the Serb and his many fans among the 17,500 present. He deserved it. Ferrer was as intense as Djokovic was distracted. If his wounded right shoulder was troubling him, Djokovic did not betray the inconvenience during play, although his error count was horrendously high by his standards, 17 in the first set, 33 overall. Ferrer's serve was razor-sharp all night – 86% in the first set – and Djokovic could not find the consistency to resist an inspired opponent. He plays his compatriot Janko Tipsarevic on Friday night. Tipsarevic earlier came so close to beating Tomas Berdych when substituting for Murray, who withdrew with a groin strain on Tuesday after losing in straight sets to Ferrer. He blew match-point in the tie-break, then fell awkwardly, hurting a knee, on the final point to lose 2-6, 6-3, 7-6. Tipsarevic caused mild embarrassment for Murray when he contradicted his version of their practice session on Sunday, 24 hours before he lost to Ferrer, before withdrawing from the tournament on Tuesday. Murray had said he "played some points" and "didn't feel good, stopped the practice early … I knew in my head I wasn't ready to play and wasn't right to play". Tipsarevic, however, said they had played for "one hour and 10 minutes". He said: "We had a long warm-up. One set. After the set, we stopped … But I … honestly never saw that he had any kind of problems on court." At the same time, Tipsarevic also said he could see that Murray "wasn't feeling great", observing that "some times players feel tired, whatever". What does it all prove? That elite athletes are finely tuned machines with their own priorities, and it underlines the minuscule margins between fitness and ill-health at the highest level. Tipsarevic, in any case, had reason to be grateful to Murray for his opportunity here and the world No9 looked to be making the most of it until he blundered at the very end of an enthralling match against Berdych. He breathed heavily, and served a double-fault to hand back the initiative. Berdych walloped a big serve wide, Tipsarevic fell awkwardly as he stretched to get the ball back and his opponent had merely to dink it into open space for the win – as his opponent should have done three shots earlier. Murray's injury replacement nursed a throbbing knee as he limped off court and prepares now for Djokovic on Friday. Berdych plays Jo-Wilfried Tsonga. The irony was, Tipsarevic had played the more sensible tennis for most of the two hours and 26 minutes it lasted, Berdych's 34 unforced errors exceeding his by 13 and it was two ill-judged forehands, one long, one short, by Berdych that gave Tipsarevic that match point. But he blew it. Would Murray have done so? Unlikely.