Peter Kowalczyk was jealous of the fact that Leona Lewis won the British TV talent show X Factor while he was turned down, according to The Sun (UK).
Naturally, he acted on that jealousy by waiting five hours to meet Leona Lewis yesterday at her book signing event, then punched her in the face.
A shocked Leona screamed and cried, "Oh my God" as the tall, buck-toothed nut job attacked, catching her on the temple with a fierce right hook.
She clutched her head and burst into tears as she was whisked away from the event (to promote her autobiography Dreams) and escorted to a hospital.
Five security guards jumped Peter Kowalczyk and pinned him to the ground. He was charged with assault before being taken to a psychiatric hospital.
Leona's furious boyfriend, Lou Al-Chamaa, who was with her at the signing, tried to confront the warped fan but was held back by the authorities.
Leona Lewis recoils in horror after having her clock cleaned.
The 2006 X Factor winner, now a global star, was checked for a concussion at London's Harley Street Hospital, but appears to have escaped with bruising.
Kowalczyk had bought a copy of Dreams and seemed to be waiting patiently for Leona Lewis to sign it at Waterstones in Piccadilly like every other fan.
But as those around him in line chatted to each other, he stayed silent and aloof. He said nothing as he reached the front and unleashed his punch.
A spokesman for Leona, whose next single is called HAPPY, said last night:
"It was totally unprovoked. Leona had been patiently signing people's books for a while - this man had been waiting for five hours. Why anyone would hit her I don't know. Leona is shaken and apologises to the fans she was unable to meet."
Waterstones said in a statement: "We would like to thank Leona for her professionalism and we are extremely sad that this event was ruined for her, and her fans, many of whom queued from the early hours of the morning to meet her."