The Association of Tennis Professionals (ATP) does not formally recognize service speed records made in Challenger tour events due to lack of uniformity in these tournaments ' radar guns (including availability or lack thereof). Nevertheless, the serve speed of 263.4 km / h (163.7 mph) recorded by Australian Sam Groth at an ATP Challenger event in Busan, South Korea in May 2012 was measured using approved equipment according to the ATP, and other data gathered appeared within a normal range. However, John Isner holds the ATP 's official record for the fastest serve at 253 km / h (157.2 mph).
who's got the fastest serve in tennis
Sam Groth