WATCH: The heartwarming moment Cher surprises fan with Alzheimer's with a FaceTime call

Cher just gave one lucky fan the surprise of a lifetime ...

Thanks to FaceTime, the 'Believe' singer shared a heartwarming moment with Erica Steiner's 60-year-old mother Robin - who has Alzheimer's - after surprising her with a phone call for almost eight minutes.

Taking to YouTube, Erica shared footage of the video call, describing it as the "greatest eight minutes" of their lives.

She also explained that the music legend has helped the family cope with Robin's diagnosis.

"Cher is basically another caregiver in our house - her presence consistently calms my mum when she's frustrated or sad," she wrote in a caption beneath the video.

At the beginning of the call, Erica tells her mum someone heard about her and wants to say hi.

After a couple of minutes of casually chatting, Robin lights up while reminiscing about the time she saw Cher in concert in Las Vegas, and after another minute, seemed to really realise that she was talking to one of her idols.

"I love you. I can't do this, it's too much," she says while getting emotional.

Awwwwww!