"If the doctors found out, they'd have told me not to play" - When Roger Federer braved through unexpected 'kissing disease' diagnosis

Roger Federer once revealed that he was diagnosed with mononucleosis in 2008 but chose to play through the illness without informing doctors. This period coincided with a dip in his form, particularly during the early part of the season.

After a dominant 2007, Federer faced setbacks in early 2008, struggling with unexpected losses at the Australian Open and during the clay season. Meanwhile, Rafael Nadal and Novak Djokovic gained momentum. The defining moment of his slump came at Wimbledon, where he fell to Nadal in a legendary final, ending his five-year reign at the All England Club.

In an interview with The Independent that year, the Swiss shared he had mononucleosis, a condition often called the "kissing disease" due to its primary transmission through saliva. Caused by the Epstein-Barr virus (EBV), mono can spread through kissing, sharing drinks or utensils, and even close contact with respiratory secretions.

"By the time they'd done one more test they said it was over already, so it was never really a case of me saying: 'Oh my God, I've got mononucleosis'. It didn't really scare me. It wasn't as though I was in bed 24 hours a day for six weeks. I could play. That was what was so amazing. I was able to get up and play a five-setter against Tipsarevic at a time when apparently my mononucleosis was at its strongest," he said.

The 20-time Major champion added:

"I hope I didn't take any health risks, because if the doctors had found out then they would have told me not to play. It was over before it started for me. When I started practising again I was feeling slow and not too good, but a month later, when I caught up with my conditioning trainer in Miami, he said how different a person I was to when I was with him just before the tournament in Dubai."