China's swimming superstar Sun Yang is looking forward to more glory on the world stage after dominating races in the country's "mini-Olympics".

Sun Yang, who represents Zhejiang province, celebrates after winning the men's 4*200m freestyle at the National Games in Tianjin on Monday.  [Photo/Xinhua]

The 25-year-old Olympic and world champion from Zhejiang province clinched the gold in the men's 800m freestyle on Monday at the 13th National Games held in Tianjin.

In the final, Sun pulled away from other finalists in the last 200 meters and clocked 7 minutes and 46.8 seconds for the gold, six seconds faster than the runner-up, Ji Xinjie from Shandong province.

"I had a cold and was feeling pretty tired. It was a tough test for me to prepare for the Games after such a short interval from the world championships. No matter how hard it is, I have to overcome the difficulties," Sun said.

It is Sun's fourth gold at the National Games, the country's highest-level multisport event, after standing on the top of podium for the 200m freestyle, 400m freestyle and 4×200 freestyle relay.

Sun is called "the king of freestyle" by his fans for his dominant performances in distance races over the past several years.

Sun rose to stardom at the 2011 world championship' in Shanghai when he grabbed gold medals in both the 800m and 1,500m freestyle. In 2012, he became the first Chinese man to win an Olympic gold in the pool after winning titles in the 400m and 1,500m freestyle at the London Olympics.

Last year, he complemented his distance collection by clinching the gold in 200m freestyle at the Rio Olympics.

Now at 25, Sun has become the leading figure on the Chinese swimming team and he was the oldest player in the pool in the 800m freestyle final on Monday. He admitted it has been not easy to keep in good shape for a long time.

"Over the past few years, I have seen off several batches of opponents. I think it is the perseverance that has kept me going forward," said Sun. "In the future, I hope to break the limit of age and strive to extend my peak performance for a longer period," he said.

As the 800m freestyle is set to become a new event at the 2020 Tokyo Olympics, Sun, who has won this category three times in succession at the world championships in 2011, 2013 and 2015, aims at adding more glory to his glittering career.

"I am looking forward to the 2020 Olympic Games. I hope I can keep pushing myself forward and show people the perseverance of Chinese swimmers," he said.

"It is challenging to simultaneously compete in multiple events. In the following training, I will spend more time on the 800m while continuing to work on other distances. I am expecting more breakthroughs," he said.

Sun, whose idol is Michael Phelps - the legendary swimmer known for covering multiple distances, is also going to compete for gold in the 1,500m freestyle and mixed 4×100m medley relay at the National Games.

Before Sun shined in the swimming pool on Monday night, spectators in the fully-packed Olympic Aquatics Center roared with excitement as another star, Ning Zetao, came up.

The Henan native clinched gold in the men's 100m freestyle in 47.92 seconds, ahead of the second-placed Yu Hexin, with a clear margin of 0.71 seconds.

"Four years ago, I competed in this gymnasium for China for the first time. Since then, I have experienced a lot and have turned into a man from a boy," the 24-year-old said after the match.

Ning rose to fame at the 17th Incheon Asian Games in 2014 when he broke the Asia record in the final of the men's 100m freestyle. At the 2015 World Championships held in Kazan, Russia, Ning became the first Asian to win the gold in the men's 100m freestyle, a distance that had been dominated by white swimmers for decades.

However, Ning suffered a slump at last year's Rio Olympics, after failing to make to the final in his favorite events, finishing 12th in the men's 100m freestyle and 30th in the 50m freestyle.