French Open tennis: Rafael Nadal reveals the pain and fear behind his return to glory

Eight-times winner will rest his knee before Wimbledon, where he is likely to be seeded No 5

Trying to persuade Rafael Nadal in recent weeks to discuss the condition of his left knee has been like asking a spy to reveal state secrets. In the wake of his historic eighth French Open triumph on Sunday, however, the Spaniard finally dropped his guard.

Despite his extraordinary comeback, which has brought him seven titles from the nine tournaments he has played since he returned in February, Nadal revealed there had been times this year when his knee hurt so much he had concerns about his future.After seven months out of the game suffering with Hoffa's syndrome – a swelling around the tendon just below the kneecap – Nadal started his comeback in a minor tournament in Chile, where he was beaten in the final by Argentina's Horacio Zeballos. "At that moment I was more worried about things other than winning or losing that match," Nadal said. "I felt a lot of pain in my knee."

The pain and fear returned in April in Barcelona, where Nadal admitted he had felt "very negative" about the knee. "Some weeks I didn't feel well," he said. "I am still going week by week, day by day." However, the best news for Nadal is that he came through seven best-of-five-set matches in a fortnight at Roland Garros. "In the last couple of weeks my knee started to feel better," he said.

In particular, the Spaniard survived a marathon against Novak Djokovic in Friday's semi-finals, trained on Saturday and felt "100 per cent" for Sunday's final against David Ferrer. Although he has pulled out of this week's grass-court tournament in Halle while he assesses his fitness following a gruelling season on clay, he plans to return at Wimbledon.

"I really hope to be ready for Wimbledon," Nadal said. "I won't play a tournament before Wimbledon, so that's not the ideal situation before a Grand Slam on grass, where the conditions are very different. The tournament is more unpredictable for that reason. But I will try to arrive in good shape at Wimbledon. And if not, I am going to look to the rest of the season because I'm in a good position, even if I don't play a good Wimbledon.

"That doesn't mean I am not going to try, because I am going to try 100 per cent to be ready and to play good tennis there. But I'm in a position where I can be a little bit more relaxed.

"Everything went much better than I thought it would [at Roland Garros], so I'm in a position where if I'm still doing the things the right way, I will have the chance to finish the year in a very good position in the rankings."

Although Nadal dropped one spot to No 5 in yesterday's updated world rankings list, with Ferrer replacing him at No 4, he is well placed to make rapid strides in the months ahead.

Because of the drop in the rankings he is set to be seeded fifth at Wimbledon, which will mean that three of the game's big four players could find themselves in the same half of the draw.

While Nadal insists that regaining the world No 1 ranking is not a target, the top spot should be well within his reach provided his knees do not give way again. He has earned 6,850 ranking points since beginning his comeback, but between now and next February he has the princely sum of 45 points to defend. To be ranked world No 5 when he has not played in two of the last three Grand Slam tournaments, or in five of the last nine Masters Series events, is an extraordinary achievement.

He insists his general level of fitness is not what it was, largely because he restricts his practice in order to nurse his troublesome knee through the season. "At the beginning of my comeback my movement was very bad," he said. "But after a few weeks I started to move well. I started to move with the right intensity. And the tennis was there."

Did he ever doubt that he would rediscover a level of performance that enabled him to become the first man ever to win the same Grand Slam title eight times?

"I am a positive person," Nadal said. "I always think positively. But doubts are part of life. People who don't have doubts are so arrogant. There are doubts in everything. I think nothing is clear in this world. So for sure I had doubts, but I worked as hard as I could to get back."

Nadal said he believed there was always room for improvement. "If you don't feel that you can improve, you know nothing about life, because nothing is perfect in this life," he said. "I don't practise because I have to: I go to practice with a goal, things that I think I need to do better to keep being competitive against the best players.

"I love sport. I understand sport in only one way. Sport without a goal is stupid. If I go and play in any sport and I don't try my best, I don't like to do it. It would be better if I did another thing. I love tennis, but I love sport in general and the spirit of sport is what really moves me."