( CNN ) -- `` I 'm not a machine , and like everybody I have better moments than others , '' Rafael Nadal told CNN in Shanghai . After a year disrupted by injury , it was a moment of candor from the down-to-Earth 23-year-old , whose winning ways on the court had at times made him seem invincible . `` Tennis is a hard sport , a very , very tough mental sport because you play a lot of matches during the season and you have to be ready every week . So you need to be very focused all the time -- 100 percent physical and mental -- if you want to have chances to have a good result . `` Sometimes you feel you need to stop . I played every week for a long time and I forgot I had to stop for an injury . '' Taking time out of the game earlier this summer to recover from tendonitis in his knees , Nadal missed out on defending his 2008 Wimbledon title , won in an epic final match against world number 1 , Roger Federer . Making his comeback just before the U.S. Open in August , he played into some form to reach the final of the Shanghai Masters tournament in October . Even though he won five major tournaments in the first half of 2009 , the lack of silverwear in the second half of 2009 is n't a worry . He retains his will to win and is happy that his job is something he loves . `` I never excepted be number two or Number one and have the chance to win Grand Slams . That 's unbelievable for me , you know , I feel I 'm a very lucky person because I work in tennis . My work is playing tennis and it 's my hobby too , you know , so not everybody can work in one of his hobbies , so I feel lucky for that , '' he told CNN . With six Grand Slam titles to his name already , the Majorcan believes he has a long future ahead of him in the game , despite his recent injury setback . `` I have seven years of my career right now and I am not finished , so I expect be here and hope be here for a long time . ''
23-year - old Spanish tennis player lost his number one ranking this year . Started season with win at French Open , but year disrupted by injury . Has won six Grand Slam title in his career so far .