U.S. golfer Tiger Woods has kept a grip on his position as the world's most valuable athlete. Forbes magazine analyzed the values of four categories of sports brands -- athletes, teams, events and businesses -- and published the results on Thursday.

Woods ranked first among athletes with an estimated brand value of US$38 million, even though the figure marked a steep drop from $82 million in 2010 and $55 million in 2011. Forbes said his income has decreased significantly as he "lost numerous sponsors in the aftermath of the bad publicity over his infidelities and subsequent divorce" and "his golf course design business has done poorly."

Swiss tennis ace Roger Federer ranked second with a brand value of $29 million. U.S. golfer Phil Mickelson, British soccer player David Beckham and NBA star LeBron James were tied for third place with $26 million each, and Jamaican sprinter Usain Bolt came seventh with $17 million.

From left, David Beckham, Roger Federer and Tiger Woods

Among sports teams, the New York Yankees had the highest brand value at $363 million to rank first. Manchester United, in England's Premier League, placed second ($293 million), followed by Real Madrid in Spain's La Liga ($255 million). Five of the top 10 were European soccer clubs.

In the sports event category, the Super Bowl took the top spot with $470 million, followed by the Summer Olympics ($348 million) and the FIFA World Cup ($147 million). The Winter Olympic Games ranked sixth with $123 million.

Nike emerged as the world's most valuable sports business worth $159 million, while U.S. sports network ESPN followed with an estimated brand value of $115 million.