Tennis: The serving speed merchants

Marius Copil has fired down the fastest serve of the Australian Open. Photo / Getty

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.

2. Sam Groth: The Australian world record holder smashed a 238km/h missile in his round two match.

1. Marius Copil: The Romanian qualifier shocked Novak Djokovic on Thursday with a series of cannonballs from the line, reaching 242km/h for his biggest serve.

Best of the big guns: Gael Monfils (216km/h), Stan Wawrinka (216km/h) and Andy Muray (214km/h).

Serve speed leaders: Women

5. Polona Hercog: The Slovakian hit 199km/h early in the week

4. Denisa Allertova: The relatively unknown Czech managed a 201km/h bullet.

3. Camila Giorgi: The Italian is only 1.68m and 54kg but hit a 203km/h serve.

2. Serena Williams: Not huge by her standards, but Williams smashed a 204km/h ace.

1. Barbora Zahlavova Strycova: The 2015 ASB Classic semi-finalist came up with an incredible 225km/h serve on Thursday.

Best of the big guns: Sam Stosur (192km/h, Venus Williams (190km/h).