Nadal: I wasn't ready for Wimbledon last year
Rafael Nadal has admitted he was not fully prepared for Wimbledon 12 months ago and insists he has nothing to prove on grass.
The world No.1 was knocked out of the tournament by Steve Darcis - a player ranked 134 places below him - in straight sets in the first round as concerns were raised about his ongoing knee problems.
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"After winning Roland Garros last year, probably emotionally, I went down a little bit after that. Last year, I was not 100% ready for the grass," Nadal said.
"I knew my knee was not perfect yet and grass is very aggressive for my knee because I need to play very low."
Nadal returned to the ATP circuit in February 2013 after spending seven months on the sidelines with a career-threatening knee injury.
The Spaniard produced one of the sport's greatest comebacks by winning two Grand Slams and eight other titles, including a record-equalling five Masters crowns. Nadal also secured the year-end world No.1 ranking for the third time in his career.
"Last year, emotionally, was a little bit of a special year because I came back after an injury of seven months with the feeling that I was not recovered," Nadal said.
"That's the real thing. I had to play the whole year with anti-inflammatories, every single match, so it was emotionally hard.
"There was a lot of success before Wimbledon, but at the same time there was a lot of suffering. Every week was tough mentally because I had to resist, then I was having to playing with pain, then with anti-inflammatory injections."
Two-time champion Nadal, though, says he is ready to mount a challenge at SW19 as he looks to avoid any repeat of the shock defeat against Darcis.
"But this year is a different story," he said. "Overall the feeling this year is better with my knee. I feel a little more comfortable running, and that's very important."
When asked whether he has anything to prove, Nadal replied: "No, the business is finished. When I won the first time, for me it was a dream come true, so that's everything. I played five finals in a row - I didn't play in 2009 - during that period I played great. I was able to win twice, I was able to be close against Roger [Federer] in 2007, too."
Nadal begins his campaign against world No.51 Martin Klizan, who was named the ATP World Tour Newcomer of the Year for 2012. Klizan comes to Wimbledon on the back of reaching the quarter-finals at Eastbourne last week - where he lost to Richard Gasquet in straight sets.