Cape Town - Chad le Clos knew he would come back stronger after winning gold on the third day of the FINA Short-Course World Championships on Thursday.
Le Clos romped to victory in 48.50 seconds - 0.21 seconds ahead of new American golden boy Caeleb Dressel - in the men's 100m butterfly in Hangzhou.
It was a fourth 100m butterfly world title for Le Clos and some compensation for the disappointment that he suffered on Tuesday.
On the first day of competition, the 26-year-old went under his own world-record time in the 200m butterfly but still came second to Japan's Daiya Seto.
The South African star admitted after the race that he needed to win Thursday's tough race.
"It was the biggest race of my short course career. I was up against the best field by far and this was the main event of the whole week," said Le Clos on Thursday.
"I am very grateful I got the gold (as) it was a tough race. I was anxious because I was waiting the whole day for this, the whole week and the past three months because I knew this one could come.
"I really wanted to race Dressel. He is the best short course yards swimmer and I am the best metres swimmer. It was difficult for him because he had the 50 metres freestyle beforehand. It is a great evening," he said.
"After the first night, people thought I was winded and I have always told them that is the biggest mistake they can make because after I have lost I come back much stronger. Tonight was important. I needed the win tonight."
Le Clos still has two events left in China, as he takes part in the men's 50m butterfly on Friday and the men's 100m freestyle on Saturday.