four separate grand slam winners last year, will miss the opening tournament after illness disrupted his recovery from a chronic knee injury. The Spaniard has not played since he lost in the second round at Wimbledon last June.
Novak Djokovic, who defeated Nadal last year in the longest final in history, made a perfect start to his season by winning the World Tennis Championship exhibition in Abu Dhabi last weekend. Victoria Azarenka is the defending women's champion.
Serbia's Novak Djokovic returns the ball to Spain's Nicolas Almagro during the final day of the Mubadala Tennis Championship in Abu Dhabi, United Arab Emirates. AP/Kamran Jebreili
African Cup of Nations
South Africa, January 19-February 10
Didier Drogba leads an Ivory Coast team packed with talent and experience and determined to atone for the disappointments of this year's tournament where they did not concede a goal but still finished runners-up to Zambia.
Ivory Coast's national football team captain Didier Drogba applauds after the FIFA World Cup 2014 friendly football match Austria vs Ivory Coast in Linz, Austria. AFP/Alexander Klein
Zambia, who defeated Ivory Coast 8-7 on penalties in the final, have kept faith with the squad who won them a first continental title.
The guide to your fix
Champions League last 16
First leg fixtures February 12-13 and 19-20.
Return matches March 5-6 and 12-13.
Final Wembley stadium May 25.
Real Madrid's Cristiano Ronaldo returns to Old Trafford, home of his former club Manchester United, in the pick of the last-16 ties which will also pit United manager Alex Ferguson against former Chelsea boss Jose Mourinho.
Real Madrid's Cristiano Ronaldo from Portugal, gestures during his Spanish La Liga soccer match against Malaga CF at the Rosaleda stadium in Malaga, Spain. AP/Sergio Torres
Ferguson's team headed the Premier League standings at the close of 2012 but Mourinho, who has been frequently linked with the Old Trafford job when the 71-year-old Scot finally decides to retire, is under pressure.
Real are third in La Liga, 16 points behind Barcelona, and Mourinho's future at Madrid is uncertain if his side are knocked out of the Champions League.
British and Irish Lions tour of Australia
June 1-July 6.
The pride of the four home nations gather for their four-yearly expedition to the southern hemisphere, this time to Australia where the Wallabies host a three-test series.
Brian O'Driscoll, the great Irish centre and a veteran of three Lions tours, is a leading candidate to captain the tour party for the second time although he has yet to play this season after ankle surgery.
A Lions' tour is one of the last great romantic sporting ventures when the best players in England, Wales, Scotland and Ireland subsume national rivalries in a greater cause. Although they have too little time to prepare after the Six Nations and club seasons, they have the talent to beat the twice world champions.
Ashes cricket series
Australia tour England for a five-test series followed by five in Australia starting at the end of the year. First test Trent Bridge, Nottingham, July 10-14.
Alastair Cook, captain of Ashes holders England, and his opposing number Michael Clarke will lead from the front after both men enjoyed wonderful years with the bat in 2012.
England cricket captain Alastair Cook speaks with coach Andy Flower during a training session at The Sardar Patel Stadium at Motera in Ahmedabad. AFP/Punit Paranjpe
Cook scored a record five centuries in his first five tests as captain and was instrumental in turning a 1-0 deficit in India into a 2-1 series win. Clarke tallied an Australian record 1,545 runs in the calendar year at an average of 106.33.
England lost more tests than they won in 2012 but in home conditions at least their bowling, headed by James Anderson who bowled magnificently in unfriendly conditions in India, should have the edge. Australia have also lost two middle-order stalwarts in Ricky Ponting and Michael Hussey who retired during the current Australian season.
World athletics championships
Moscow August 10-18
Usain Bolt, the only man to retain the Olympic 100 and 200 metres titles, has already set his goals for the 2013 season.
Usain Bolt of Jamaica, crosses the finish line ahead of Ryan Bailey, of the United States, to win the men's 4x100-meter relay final and set a new world record with a time of 36.84 seconds during the athletics in the Olympic Park at the 2012 Summer Olympics in London. AP/Matt Dunham
Bolt says he will concentrate on speed and on winning back the world 100 title he relinquished to Jamaican training partner Yohan Blake in Daegu in 2011 after false-starting in the final.
Another London Olympics double gold medallist, Britain's Mo Farah, plans to run both the 5,000 and 10,000 in Moscow before considering a possible move up to the marathon.