George Opelka, father of American tennis player Reilly Opelka, has spoken out in support of Novak Djokovic, following some comments by former tennis player Rennae Stubbs on the Serbian's legacy.

"I think Roger Federer and Rafael Nadal definitely personified wanting to win a lot but it's obsessive to Novak and you can see it," said Stubbs. "He wants to put the numbers up because he knows he's not gonna be as popular worldwide as Roger and Rafa."

The senior Opelka took offence to Stubbs' recent comments, stating the World No.1 was leaving a legacy that went beyond trophies and popularity contests.

"Novak is just wired different. His legacy is still being written and it extends beyond popularity contests, record books and his trophy case. If the media wants to focus on popularity contests, be sure to check in with the locker room too," wrote George Opelka on Twitter.