Swimmer Kosuke Kitajima knows his position on the national team is no guarantee for the world championships in Shanghai this July. And it is his Japanese rivals who are raising the bar in the level of competition.

"I'm sure this year's national championships will be an extremely tough one," the two-time double Olympic breaststroke champion told reporters Friday at Tokyo Tatsumi International Swimming Center.

"The level of competition is getting higher in Japan. Not only (Naoya) Tomita but many other strong swimmers are out there in breaststroke. You can't just go out and win easily."

Kitajima, who now lives in California, is back in his country to compete at the short-course Japan Swimming Championships this weekend as part of his preparations for the national championships in April.

Kitajima, 28, is scheduled to swim in the 100-meter breaststroke on Saturday and the 50 and 200 on Sunday.