Ferrer floors No. 1 DjokovicLONDON – Defending champion Roger Federer maintained his 100 percent record at this year's ATP World Tour Finals by completing his group fixtures with a 6-1, 3-6, 6-3 victory over America's Mardy Fish Thursday. Federer was already guaranteed top spot in Group B and a place in the semifinals after winning his first two matches and the Swiss survived a mid-match wobble against Fish to extend his impressive run at London's O2 Arena. Federer's 37th career Tour Finals victory moved him into second place on the all-time list ahead of Boris Becker and he is only two wins behind leader Ivan Lendl. His semifinal opponent is still to be decided, but if Federer can maintain this impressive form it would be no surprise to see him win the tournament for a record sixth time and equal Lendl's tally of victories in the process. In contrast, Fish, who was already out of contention for a semifinal spot after losing against Rafael Nadal and Jo-Wilfried Tsonga, ends his first visit to the season finale without a win. “It is great to have won all three matches in the group stages. I have had a great run since the US Open and I'm still going strong,” Federer said. While Andy Murray is out of the tournament due to a groin injury and Rafael Nadal and Novak Djokovic are weary at the end of a gruelling campaign, Federer, who is now on a 15-match winning run, looks fresher than ever. On Wednesday, David Ferrer, the lesser known Spaniard in the ATP World Tour Finals, burst out of Rafa Nadal's shadow to reach the last four with a demolition job on world No. 1 Djokovic 6-3, 6-1. “I have no words to explain this match,” Djokovic, who went on a 41-match winning rampage at the start of the year and claimed three of the year's four majors, told reporters. “Nothing was going well. I don't play at least 50 percent better than I did tonight, I don't think I'll have any chance. You always hope that tomorrow will bring something better.” In front of another sell-out crowd in the 17,500-capacity arena, Djokovic began solidly enough as the first six games of the match went with serve. However, when the terrier-like Ferrer raced across court on break point to whip a forehand down the line that caught his opponent flat-footed at the net, the match ceased to become a real contest as the 29-year-old from Valencia ran way with it. He broke the Djokovic serve again to win the opening set and he needed nothing spectacular in the second set as Djokovic offered little resistance. The Serb's mounting unforced error tally spoke volumes. “I'm embarrassed to look at the stats,” Djokovic, who made 33 unforced errors, said. “All credit to my opponent, he played a great match.”