Greg Rusedski was hit in his privates at the opening of a new 1.2 million-pound-tennis centre in Portsmouth, Hampshire.
The 40-year-old tennis player was teaching a youngster to hit the ball when he was smacked by the young boy, the Mirror reported.
However, the former British number one was quick to play down the balls up and laughed as he doubled over and said "oooh".
The incident was caught on camera and quickly uploaded to YouTube.
Jo Dallas, centre manager, said that Rusedski came down to officially open the new tennis centre and he was a great sport, happy to spend time with everyone.
He added that it was a bit unfortunate with the incident on the video but he took it well.
