Greg Rusedski
Most fans will remember Greg Rusedski as the winner of the Grand Slam in 1999. He also made headlines when in 1997, he made it to the US Open as a finalist and received the title of BBC Sports Personality of the Year and the ITV Sports Champion of the Year. He can also be remembered as the man who served the 16th fastest tennis serve at 239.8 km/h (149 mph) during the 1998 Newsweek Champions Cup.
Juan Martín Del Potro
The professional Argentinian tennis player is currently ranked at number 11 in men’s singles in the world. He won the US Open in 2009, bringing him his first Grand Slam title. Just recently at the 2017 Stockholm Open, he clocked 240 km/h (149.1 mph) with a serve that made him the 15th fastest server in tennis history.