Chinese star swimmer Sun Yang opens his 2018 season with an effortless win in the 200-meter freestyle at the national championships, launching preparation for his multiple-gold 2020 Olympics campaign.

Even with the physical challenge of the over 800m altitude of Taiyuan, the capital of Shanxi province, Sun managed to maintain his lead throughout the 200m course to win his first event at the 2018 National Championships in 1 min 46.07 sec at the Shanxi Sports Center Natatorium on Friday evening.

Ji Xinjie of Shandong finished 0.73 later while Sun's Zhejiang teammate Wang Shun won the bronze medal in 1:47.21 at the annual championships, which serves as a domestic trail for the 2018 Indonesia Asian Games.

Sun's winning result only ranks fifth so far this season. Lithuanian rising star Danas Rapsys leads the board currently with his astonishing win in the 200m freestyle in 1:45.12 at the Stockholm Open last week.

Although the result fell way behind his best ability, Sun remains confident that he has what it takes to maintain his supremacy in freestyle in the world.

"For me, I've always set my eyes on international competitions and I only take domestic meets as training. The result here doesn't matter," said Sun, who became the first Chinese man to win Olympic gold medals in swimming at the 2012 London Games in the 400m and 1,500m events.

After extending his freestyle prowess to shorter distances by winning gold in the 200m at the 2016 Rio Olympics, Sun said his goal for Tokyo 2020 is to maintain his dominance across the sprinting and distance events to win as many gold medals as possible at what is expected as his last Olympics.

"I am planning to compete in four individual free events in Tokyo (from 200m to 1,500m) as far as what I am capable now," said Sun, who has won nine world championship titles in four distances since 2011.

"It doesn't mean that I have to win all four gold medals as a target. But to maintain my lead ahead of the world in my strength events - 200m and 400m -- I have to keep my aerobic endurance and stamina at a high level by training in the 800m and 1,500m as well.

"I've just pulled through a tough training program in Australia with an emphasis on my endurance capacity. I am very confident in myself that I can sustain the challenge of competing in multiple distances."