QINGDAO, China, May 4 (Xinhua) -- After a two-year setback, 2017 world medalist Li Bingjie won her favorite 400m freestyle with a time of 4:02.36, a personal second-best and world third-best this year at the Chinese National Swimming Championships here on Sunday.

Meanwhile, in the 200m freestyle final on Tuesday, Li grabbed silver with her personal best of 1:56.64, coming back strong from the lows of her career.

As China's hope in women's mid-distance and long-distance freestyle, the 15-year-old Li shone at the 2017 World Championships in Budapest, winning bronze in 400m freestyle and silver in 800m, and set two Asian records at the National Games later that year.

However, Li has suffered a slump since then, with injuries early last year keeping her away from training and competition. Many feared that the "wonder girl" would flop as it seemed.

The 19-year-old admitted that she was devastated but has never thought of giving up. "I was really frustrated during the bad days, but I try not to show it," said Li. "I knew I would come back strong as long as I could find the problem. I will never give up like that."

Li worked hard to make up for her physical weakness by taking physical training sessions three times a week. 15 laps on the track field seemed normal for her but 100 laps could also happen when she didn't perform well.

"I used to work on what I'm already good at," Li noted. "But now I work on my weaknesses instead. I can see how I've changed."

Practice makes perfect. Li snatched the women's 1,500m freestyle gold with her personal best of 15:52.31 at the Chinese Swimming Challenge in January and claimed gold in the 400m freestyle with a time of 4:02.36, third-best in the world this year and just 0.61 seconds slower than her own Asian record.

"It was better than I expected," said Li. "I have never competing in the morning before, but now I'm getting used to it and I'm training accordingly."

Looking at the Tokyo Olympics, Li seems driven but calm. "I will try to set a higher goal. But I will focus on my training as of now."