Serbian tennis star Novak Djokovic aims to reclaim the world number one spot by the end of the year, he said during a promotional tour to Taipei. Djokovic was knocked off the world number one ranking when Swiss legend Roger Federer won his seventh Wimbledon title and 17th career grand slam title in July to reclaim the position he last held in May 2010. ``That's one of the goals. Of course I want to be number one of the world again. It's an ambition. It's possible (by) the end of the year,'' Djokovic told reporters. ``I try to focus on each tournament individually and see how it goes. I need to play really well because there are so many great players in this moment ... so we'll see.'' After a remarkable 2011, when he recorded one of the greatest individual seasons in tennis history and a dominant start to 2012, Djokovic has come up short in the last three grand slams. He lost to Rafael Nadal in the French Open final followed by a semi-final loss to Federer at Wimbledon. Most recently, he lost his 2011 US Open crown to Scotsman Andy Murray earlier this month. AAP. Will he do it?