Abstract: A tennis ball pressurizer having a source of pressurized gas, a regulating valve for controllably releasing the gas and a hollow needle for injecting the gas into the ball. The needle has an internal bevel at one end which cuts a plug from the wall of the ball. The plug seats into the needle and is partially exposed beyond the end of the needle. Gas is released from the pressure source and passes through the needle to enter into the ball through a side vent in the needle. As the needle is withdrawn from the ball after it is repressurized, the plug engages in and seals the puncture hole.