Ajla Tomljanović and her joke after the game with Serena Williams.

Ajla Tomljanović started the match well, breaking Serena Williams in the opening game.

But the 23-time grand slam champion quickly got back on level terms, before Ajla Tomljanović regained her composure to take the first set.

The second set was a much tighter affair, with neither player able to gain a decisive advantage.

Ajla Tomljanović had two chances to serve out the set at 5-4 and 6-5, but Williams held firm to force a tie-break.

And it was the American who prevailed in the breaker, winning 7-5 to take the match into a deciding set.

But Ajla Tomljanović was not to be denied, breaking Williams in the opening game of the third set and never looking back as she closed out a famous victory.

After the match, Ajla Tomljanović was asked whether she had been nervous playing against such a legendary opponent.

“I was joking with my coach before the match that I have nothing to lose,” Ajla Tomljanović said.

“I’m just going to go out there and swing away and enjoy every moment.”