We look back at the serving kings and queens over the first four days of the Australian Open, as a low profile Czech player tops Serena Williams and the mens' world record holder is trumped by an unknown Romanian.
Serve Speed leaders: Men
5. Fernando Verdasco : The 2009 semi finalist here has pounded down a 229km/h bomb.
4. John Isner: The two time Heineken Open champion hit 230km/h earlier this week.
3. Marcel Granollers: The Spanish doubles specialist matched Isner's 230km/h.