Can Rafael Nadal recover to reign again? The Chile Open at Viña del Mar is on the lowest tier of tournaments on the men's circuit, offering just 250 ranking points and $74,000 (£47,000) to the winner, but the eyes of the tennis world will be on the seaside resort this week. The interest is already such that when the top seed arrived in Santiago three days ago he was whisked off to an hour-long meeting with Sebastian Pinera, the country's president. The attraction for the president was the chance to meet the king. Rafael Nadal, the king of clay, is the No 1 seed at Vina del Mar in his first tournament since he was swept aside by Lukas Rosol in the second round at Wimbledon last summer. Nadal has spent the last seven months nursing his latest knee injury and the question now is whether the 26-year-old Spaniard can ever rescale the heights which brought him a record seven French Opens and a place among the elite group of men who have won singles titles at all four Grand Slam tournaments. In his absence the major trophies have been won by Andy Murray and Novak Djokovic, who are rapidly replacing Nadal and Roger Federer as the sport's headline rivalry. Nadal, whose immensely physical style has always put huge strain on his body, has a history of knee trouble. In the past he has recovered - eventually - to recapture his old form, but this has been his longest absence. The latest problem flared up in February last year, though he soldiered on until Wimbledon. The injury was diagnosed as a partially torn tendon, which caused a swelling - known as Hoffa's syndrome - below the left kneecap. Despite intensive physiotherapy and laser treatment, a comeback has been repeatedly postponed. The Australian Open had been a long-term target, but Nadal's recovery programme was disrupted by a stomach infection. He is now returning in three low-key events - after Chile he goes to the Brazil Open in Sao Paulo and the Mexico Open in Acapulco - to give himself a chance to assess his recovery while playing on clay, the surface which has given him fewest knee problems in the past. He will return with a new racket, having asked Babolat to provide one that will help him put even more top spin on the ball. Nadal said his knee was "much better" but admitted it was still causing him pain, although he was not risking a more serious injury by playing. "I'll have to be patient," he said at a pre-tournament press conference. I need to gain competition rhythm as soon as possible and I hope this tournament helps me get there. The Spaniard, who has already dropped to No 5 in the world rankings and will rapidly plummet further if he does not start winning tournaments soon, hopes to return to the main circuit next month for the hard-court Masters Series events at Indian Wells and Miami, though he may be tempted to stay on clay until the end of the French Open in June. "Tennis is a very aggressive and demanding sport and obviously the knees suffer above all when you are playing on hard courts," Nadal said. On fast courts the movements are much more aggressive. When you are playing at your maximum you have to push your body to the limit. I'm prepared to accept that at the start my knee might not respond well and I may have to take it easy, mixing periods of play and rest for the first three months. Andre Agassi, who returned to the top after a lengthy spell out of the sport in the 1990s, believes Nadal can recapture former glories but says it may take him more than a year to do so. "I found whatever time you take away from the game you need that time doubled to be fully where you were when you left," Agassi said at last month's Australian Open. If he comes back in the first half of the year, you won't see him at his best, historically speaking with my experience, until this tournament next year. A fear for Nadal could be that the sport has moved on, even in the last year, with Djokovic and Murray leading the way with their remarkable athleticism and powers of endurance. The peaks to be re-climbed are clearly higher today than they were even in Agassi's time. Juan Martin del Potro, for example, missed almost all of 2010 with a wrist injury and has yet to recapture the form that saw him win the 2009 US Open. Gaël Monfils, the outstanding junior player of the Nadal-Murray-Djokovic generation, has repeatedly struggled after spells of knee trouble. Lleyton Hewitt, only six months older than Federer but dogged by injury in recent years, has never come close to rediscovering the magic that took him to the top. Tommy Haas, who has probably had more injuries than Nadal has had plates of paella, David Nalbandian and Nikolay Davydenko are all further examples of leading players who have never been quite the same following lengthy periods out of the game. Federer, nevertheless, is optimistic about his old rival's prospects and welcomes his return. "The game's obviously stronger with him than without, but you kind of move on," Federer said. It's a very fast-moving sport. But my feeling tells me when he is back he will be strong and he will be very difficult to beat. Obviously on the clay he hardly loses any matches. We're looking forward to that moment. It's going to be good energy for the tour. Nadal, who can at least draw on apparently bottomless reserves of mental strength, is philosophical about his situation. "The reality is that at the age of 26 and after a career of more than 10 years, with very good results, it has been my good fortune that my knees have not prevented me competing at the highest level for many years," he said. I'm confident I have plenty of years ahead. What I want is to recover well and to continue enjoying tennis and competition, which is what makes me happy right now. 2004 Suffered stress fracture to left ankle while playing in Portugal. Out of game for three months but won first senior title of his career in Poland in August five tournaments into his comeback. 2006 Won Madrid indoor title in October 2005 but was out for next four months because of bone problem in bridge of left foot. Missed Australian Open and returned in February in Marseille. Beat Roger Federer in final to claim Dubai title in second comeback tournament. 2009 Suffering from tendinitis in both knees, Nadal lost to Robin Soderling in fourth round of French Open, his only defeat in eight visits to Roland Garros. Missed Wimbledon, returned to competition in August but lost 12 out of 14 matches against fellow top 10 players during 11-month run without a title, which finally ended at following year's Monte Carlo Masters. Nadal 36 career titles on clay, win percentage 93.0; Bjorn Borg 30 titles, 86.3pc wins; Ivan Lendl 28 titles, 81.4pc wins; Guillermo Vilas 45 titles, 79.6pc wins. The recent period of inactivity has enabled Nadal to learn new skills. He has just won his first poker tournament on the website of his sponsors, PokerStars, beating 46 rivals to claim the first prize of €152.40.