This is Why Roger Federer is a Legend (Only Fair Play)

Roger Federer stopped serving against Stanislas Wawrinka during ATP World Tour - Basel 2011 Semi-Final when he realized a mistake with score. Actual score supposed to be 30-30 but my mistake it was shown as 40-15 (in favor of Federer). Hence, Federer talked to the chair umpire and convinced him to change the score to 30-30. What a fair player!