Former world number one Caroline Wozniacki will retire after the Australian Open, calling time on her playing career before she turns 30.

The 2018 Australian Open champion, who won 30 WTA singles titles, plans to focus on her life away from tennis and hopes to start a family.

At 29, it is an early departure for the Dane, who is ranked inside the world's top 40.

But how much do you remember about other tennis stars who decided to hang up their racquet at an early age?

Take our quiz below to find out...