Roger Federer says that despite winning just one title this season, 2013 was not a “lost year,” and adds that the criticism against him isn’t justified.

“In the circumstances, it was actually an interesting season,” Federer told the website of his sponsor, Credit Suisse. “It’s no joke being injured, of course. But I had to get through it, I had to question everything. Along with the back problems, I had other setbacks of a kind I had seldom had in the previous ten years. But nonetheless it was an interesting experience -- to see how different people reacted, and how I dealt with this situation myself. Sometimes, I could hardly move properly, and yet was sharply criticized by some people.”

Federer admitted that his loss to Sergiy Stakhovsky in the second round of Wimbledon was one of the biggest disappointments of his season.

“I went to Wimbledon convinced that I could win the tournament for the eighth time,” he said. “But it wasn’t a complete surprise for me. Because I hadn’t played really well in Paris. Then Wimbledon was the start of the bigger problems.”

The 32-year-old also said that losing to lower-ranked players has not taken away his enjoyment of the sport.

“Defeats are part of tennis,” said Federer, who also added that he could still compete with the best. “What matters is how you react. What is also important for me is that I am honest with myself. I am the sort of person who often questions everything; I did the same when things were going really well for me. That’s why I am not affected much by the criticism, which I don’t think is justified.”