Look out, Williams sisters, there's a new kid on the courts, and she's got room to grow.
The pint-sized phenom came to South Florida from Australia with her father to study under the illustrious Rick Macy, who thinks he's got a heavy hitter on his hands.
"I've never seen anybody with feet like this, and she has very good hand eye coordination for four, it's uncanny," Macy told WPTV. "This is the scariest little creature I've ever seen."
Macy has been training with Lines for a month at his tennis academy at Boca Lago and Mia's father Glenn says a future in tennis is his daughter's destiny.
"The first thing Mia ever saw coming out of her mother was a tennis ball. I used to wave the ball above her head and put ping pong paddles in her hand and work on her motion," said Glenn Lines.
The junior jock said she see no reason why she can't be one of the elite when she gets a little bigger.
"I'm gonna still play tennis," Mia said.
And what tournaments would she like to win?
"Wimbledon, Australian Open, French Open, US Open."
Macy said he doesn't know how high her star will shoot, but it's never bad to get an early start.
"I don't have a crystal ball, and I've been wrong too, but I know there's a place for this little kid on the pro tour, whether it's 50, 40, number 10 or winning grand slams," Macy said.
Father Glenn isn't pushing too hard, saying whatever his daughter does, she chooses her own path.
"At the end of the day, if she went professional I'd love that. If she won Wimbledon, I'd love that too, but she drives the bus."