Agent: Federer had mono at Aussie Open (AP): "Roger Federer couldn't figure out why he felt so sluggish at the start of this season. His doctors eventually gave him an explanation: The world's No. 1 tennis player had mononucleosis. 'Roger found out he had mono, and didn't know it. He found out a couple of weeks ago. That's probably what was wrong with him,' Federer's agent, Tony Godsick, said Friday."
Yahoo! Sports - Tennis News - http://sports.yahoo.com/ten