Top Spin 4

Found a simple way to do this. Return each ball with a power slice (x button held down) to the opposite side while holding down.

Example: if you're on the right side of the court, return with while holding the joystick down-downleft
And if you're on the left side down-downright.

*EDIT*
I've just obtained this achievement a couple of times again and noticed it's pretty simple with Andy Murray on a clay court. I choose the one all the way to the right.

I got it 3 times with an under shot and once with a perfect. Also, try standing between the base line and the middle line. As well as placing Eugenie Bouchard as the CPU since she's the lowest skilled player you can take on.