Karlovic 's game evolves around his serve , if it were n't for his serve he probably would n't be in the ATP top 100 .
Karlovic has a biomechanically more effective serve than Federer 's .
Karlovic 's game evolves around Karlovic 's serve , if it were n't for his serve he probably would n't be in the ATP top 100 .
Karlovic has a biomechanically more effective serve than Federer 's .