We usually say, “X has the ball” or “The ball is in X’s court”
The ball is in X’s court --> Tennis reference. They must take action to return the ball or you lose.
X has the ball --> Football reference (pick your flavour of football—I spelt flavour with a ‘u’ so I’ll take either soccer or Aussie Rules). You have the object of importance and the other guy doesn’t. They better stop you before you can press your advantage.
The ball is in X’s court --> Tennis reference. They must take action to return the ball or you lose.
X has the ball --> Football reference (pick your flavour of football—I spelt flavour with a ‘u’ so I’ll take either soccer or Aussie Rules). You have the object of importance and the other guy doesn’t. They better stop you before you can press your advantage.
This is the first I’ve heard of the second.