10. Roger Federer: The Federer Era blossomed from 2003-09. During this period, the tennis legend captured a whopping 15 grand slam singles titles.
He started fading away in 2010, but still had one grand slam and the No. 1 ranking at the beginning of the year.
2011 was the first time after 2002 that the year didn't see a Federer grand slam title. And to make matters worse, he's ranked No. 3!
Image: Roger Federer from Switzerland reacts after he lost the match to Serbia's Novak Djokovic during the second day of Abu Dhabi Mubadala Tennis Championship, Friday, December 30, 2011 in Abu Dhabi, United Arab Emirates.