Stop Chart Plotting at 0 when variable is not part of data series

Hi,

I am trying to plot a chart to represent the flight of a ball through the air. I have three sets of data points representing the X (Distance), Y (Direction) & Z (Height) coordinates of the ball as it flies through the air. I am trying to plot two sets of data series namely X against Z (to represent the distance/height) and X against Y (to represent distance/direction). I want the graphing to stop when the ball hits the ground (i.e. when Z = 0). I can do this OK when charting X against Z but do not know how to do it when charting X against Y (when Z is not a variable in the Data Series). Can anyone please offer any help.

Many Thanks,

Andy.