Sam Querrey says Roger Federer has the ‘biggest impact’ on tennis ahead of Novak Djokovic‎

Roger Federer, Novak Djokovic and Rafael Nadal are widely considered to be the three greatest players in men’s tennis history. Djokovic is perhaps the greatest: he has won the most Grand Slam singles titles in men’s tennis history [24], and leads Nadal and Federer in almost all major statistical categories.