BEIJING, July 17 -- Chinese Olympic champion Sun Yang confirmed on Friday that he will compete in the men's 200m, 400m, 800m and 1,500m freestyle at the upcoming swimming World Championships in Kazan, Russia.

The 23-year-old Sun, who claimed three gold medals at the 2013 Barcelona worlds, has kept a low key about his medal prospect at Kazan.

"I don't expect to win all the four titles," he said. "But I do have something in my mind, and you will know it at the competition."

Sun is favored to win the men's 200m free title, as Olympic champion Yannick Agnel and Asian champion Kosuke Hagino both have decided to skip the worlds due to injuries. Sun's old rival, South Korean Park Tae-Hwan will also miss the worlds over a doping ban.

"There will be some top swimmers taking part in the worlds, like Australia's Mike Horton. What I should do is to stay focused on my own training," said Sun, who just came back from a training session in Australia.

"It's winter in Australia now, and outdoor training is very difficult. But I've made some improvement in strength and speed," he said.

The Chinese swimming team will leave for Kazan on July 27.