The 44-year-old singer had a strong friendship with the music legend, who tragically passed away in December last year, but one of their first outings together saw the former Spice Girls singer accidentally ''walloped'' in the face by her pal when they were dancing to George's own 1996 hit single 'Fast Love'.
Speaking to the Metro newspaper about her memories of the 'Careless Whisper' hitmaker, she said: ''I went clubbing with George Michael when I first started hanging out with him. Remember, I'm a fan.
''It was the time of 'Fast Love'. We were both on the dance floor in the South of France. They put his record on, he was doing the moves and accidentally smacked me in the head.''
Geri was left too ''stunned'' to know how to respond by the accidental smack.
She continued: ''I was looking at him stunned. This was early days of knowing him and I had been walloped in the face by George.''
Geri's latest single, 'Angels In Chain's, has been written in tribute to her late friend and she admitted she spent the whole of the writing and recording process questioning whether or not George would have approved of the track.
The star - who has 11-year-old daughter Bluebell with a former partner and four-month-old son Monty George with her husband Christian Horner - said: ''I've asked myself every step of the way what he would think. Would he approve? I haven't done it perfectly but I've tried to keep him in mind.''
Many ticket-holders couldn't get into the O2 Arena show on Tuesday night (September 19th) because they didn't bring photo ID to match their booking.
An album re-release, a new song and a documentary mark the singer's legacy this year.
The actor plays the titular hero in the forthcoming adaptation.