Australian Samuel Groth, the world No.340, has broken the record for the fastest serve in tennis with a 263km/h missile during a challenger tournament at Busan in South Korea, the ATP announced on Saturday.

The record had been held by giant Croat Ivo Karlovic, who fired down a 251km/h serve during a Davis Cup match against Germany in March 2011.

Groth, 24 – the former husband of Australian Jarmila Gajdosova – broke the record in a loss to Uladzimir Ignatik of Belarus in the second round of the challenger event.

During the match, he also produced serves timed at 253.5km/h and 255.7km/h.

Groth reached his highest ATP ranking of 220 in November 2009. He was born in Narrandera but bases himself in Melbourne.