Brazil's Cesar Cielo admitted he was relieved to have retained his men's 50m butterfly title on Monday at swimming's world championships, just 10 months after surgery on both knees.

Cielo claimed gold in a winning time of 23.01sec with Eugene Godsoe of the US just four hundredths of a second behind claiming silver and France's Frederick Bousquet at 0.10 sec back to win bronze.

With five gold medals from the past three world championships, Cielo exploded with delight when his victory was confirmed after a difficult buildup to Barcelona.

"It was very tense, very nervous and my finish made all the difference," said Cielo, a sprint specialist, who won the world 50m butterfly and freestyle titles in Shanghai two years ago.

After winning bronze in the 50m freestyle at the London Olympics, Cielo underwent surgery on his knees at the end of 2012 and admitted he was concerned the impact that would have on his performance in Barcelona.

"It was a really hard time for me after the Olympics," said the 26-year-old, who won the 50m freestyle Olympic gold at Beijing 2008.

"Right now, I'm 10 months on from the surgery and looking forward to some time off. Now I am going to focus on getting my knees back to 100 percent.

"I'm comfortable talking about my knees again: for the first three months after surgery I just wanted to practice and go home, I didn't want anyone to see me swimming the way I was practicing.

"I couldn't push off the wall for two months. I only started kicking again back in March, so it was a tough time.

"I'm not feeling 100 percent just yet, because we didn't have time in training to get to full fitness, but I'm feeling very fast.

"I'm not as powerful, because I wasn't able to do squats in the gym or do any heavy weights, so we tried to focus on being fast and it worked.

"I want to thank my coach for implementing that vision.

"We tried to build the muscles in the way I was going to be able to use them effectively, so to win the gold medal is a huge relief."

The Brazilian started working with a new coach Scott Goodrich at Auburn University in Alabama earlier this year and Cielo said the move has paid off.

"I think the main change was having a new coach this year. I started to work with a guy who used to be my roommate in college," said the Brazilian.

"He is 27 and it was a little bit of a crazy idea to start working together.

"I felt like after the surgery I needed a fresh start with a fresh mentality to get better results after the Olympics.

"A lot of times during the season I had doubts and didn't know what was going to happen and I think he is the main reason for me starting back again and getting to the top."

(China Daily 07/31/2013 page22)