Japan\'s four-time Olympic swimming champion Kosuke Kitajima thinks the challenge from his compatriots is tougher than ever, as he bids to qualify for the London Games and go for a third consecutive golden double. The 29-year-old, who retained the 100m and 200m Olympic breaststroke titles at the 2008 Beijing Games, must finish first or second in each distance at the Japanese national championships starting Monday to book a ticket to London. Other Olympic title hopefuls competing at the week-long event in Tokyo include world silver medallists Takeshi Matsuda and Ryosuke Irie. \"Four years ago, I made the national team with ease,\" Kitajima told Japanese media in Columbus, Ohio, in March when he won the 100m and 200m at a US swimming Grand Prix series meeting. \"I don\'t feel it easy to qualify for the Olympics this time. It is tough in some aspects and there is the pressure. But I have to stay strong because of that.\" Plagued by injuries, Kitajima has been far from unbeatable in the breaststroke even at home since he moved his training base to the US city of Los Angeles after the Beijing Olympics. His teammate Ryo Tateishi won the 100m at the 2010 Asian Games where Kitajima finished fourth in both the 50m and 100m before pulling out of the 200m, citing nagging pain in his shoulder and joints. At last year\'s nationals, which served as trials for the 2011 World Championships, Kitajima won the 100m but in the 200m he came second to Asian Games 200m champion Naoya Tomita and suffered a leg injury. There is also a new rival on the horizon in the form of 17-year-old high-school student Akihiro Yamaguchi, dubbed \"Kitajima II\", who has posted a series of quick breaststroke times. Japan Swimming Federation executive director Koji Ueno told reporters, however, that Kitajima \"has been shaping up like never before... There is a huge difference when compared with how he was last year\". At the World Championships in Shanghai in July 2011, Kitajima finished runner-up to Daniel Gyurta of Hungary in the 200m. He was fourth in the 100m which was won by Alexander Dale Oen of Norway in 58.71. To put pressure on his international rivals, Kitajima will need to clock below 59 seconds in the 100m and below 2min 8sec in the 200m. Meanwhile, in the men\'s butterfly, Matsuda hopes to catch up with American Michael Phelps who beat him in the 200m at the Shanghai World Championships by 0.27 seconds. \"If I can\'t better Phelps\'s time (1:53.34) at the nationals, I will never get the gold medal at the London Olympics,\" said Matsuda, 27, who won the 200m bronze in Beijing behind Phelps and Hungary\'s Laszlo Cseh. Irie, 22, who came second to Ryan Lochte in the 200m backstroke in Shanghai, hopes to close in on the American. He clocked 1:54.11 against Lochte\'s 1:52.96 in Shanghai. In the women\'s contest, the focus will be on world 50m backstroke silver medallist Aya Terakawa.