"I heard a couple of steps and then I just saw this (flash) and the next thing I knew was I was on the ground," the Def Leppard drummer, 59, told ABC's Good Morning America in an interview broadcast on Monday.

"I landed on my backside - hit my head on the pavement."

Def Leppard were in Fort Lauderdale to perform at the Seminole Hard Rock Hotel and Casino when Allen was attacked on 13 March while smoking a cigarette outside a hotel.

Police arrested Max Hartley, a 19-year-old from Avon, Ohio, who has pleaded not guilty to two counts of battery and four counts of criminal mischief, according to court records.

Police said they have yet to determine a motive.

"I don't think he knew who I was, but he must have seen that I wasn't a threat because, you know, I've only got one arm," said Allen, who lost his left arm in a car accident in 1984.

According to the police report, Hartley was allegedly hiding behind a pillar outside the hotel and then ran at Allen, knocking him to the ground.

He also allegedly attacked a woman who tried to help Allen, but she was not seriously injured.

Hartley allegedly then ran to another hotel and started breaking car windows until he was stopped by witnesses and police arrived, police said.

Hartley's lawyer, Kevin Gardiner, did not immediately reply to an email seeking comment about the case.

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Allen's head struck the ground during the attack, and he and his wife, Lauren Monroe, told Good Morning America that they have been focusing on his recovery.

"My heart just completely sank into me. I know the journey of trauma. Everything stopped in our house and focused on him," Monroe said.

The couple created the Raven Drum Foundation to help survivors of trauma, especially veterans and first responders, in 2001.

Allen and his bandmates performed at a small venue in their home city of Sheffield on Friday before kicking off their European tour.

"I know that I'm not going to be playing music in a band forever," said Allen.

"But while I am, I plan on making as many people happy as I possibly can. And this is my time. This is my opportunity."