Double amputee track sensation Oscar Pistorius has taken a step closer to taking part in the London Olympics next year after clocking a qualifying time of 45.07 seconds for the 400 metres. The South African known as the \"Blade Runner\", who runs with carbon fibre prosthetic running blades, finished clear of the field in Lignano, Italy, on Tuesday as he smashed his personal best of 45.61sec. Importantly, he dipped under the crucial 45.25sec qualifying mark, meaning the 24-year-old four-time Paralympic gold medallist will become the first amputee sprinter to compete at the World Championships which get under way in Daegu, South Korea, on August 27. \"Needed a 45.25 A standard, ran a 45.07sec!\" Pistorius said on his Twitter account, singling out coach Ampie Louw for thanks. \"Thank you to my team, Ampie especially. \"Feels kind of surreal to have an A-qualification time in the bag for next year\'s Olympic Games. \"Thank you all for your support. He added: \"Can\'t sleep I\'m so happy. I have a dumb smile that\'s permanent!\" Pistorius, who had both legs amputated below the knee when he was 11 months old because of a congenital condition that meant he was born without fibulae - lower leg bones, failed to qualify for the 400m at the 2008 Beijing Olympics. He had been given the green light to attempt to qualify for the Beijing Games after the Court of Arbitration for Sport overturned a ruling by the International Association of Athletics Federations that his blades gave him an unfair advantage. Pistorius\'s previous personal best of 45.61 seconds was inside the \'B\' standard set by the IAAF for the event but meant he was unlikely to make the South African team. Every national federation can select three athletes for the world championships or Olympics, providing they meet the \'A\' standard, with only one allowed if they only meet the \'B\' standard. Before his outing on Tuesday, Pistorius was only ranked fourth among South African 400m runners behind LJ van Zyl, Ofentse Mogawane and Lebogang Moeng. His new personal best of 45.07sec, good enough for fifth at the Beijing Games and fourth at the Berlin worlds in 2009, was 0.18 seconds inside the \'A\' standard time. Pistorius will also compete at the London 2012 Paralympics where he will look to retain his titles in the T44 100, 200 and 400m.