The Magnus Effect

Spin bends a ball because the rotating surface changes how air sticks to and separates from each side. That asymmetric boundary-layer separation deflects the wake one way, and the ball is pushed the other way.

You can describe the result as a pressure difference, but the cause is not simply "faster air by Bernoulli." The key is viscosity, surface motion, and wake deflection. That is why topspin makes a tennis ball dive and backspin helps a golf ball stay aloft.