Liza Minnelli performs at the Luxor Hotel and Casino. Las Vegas, Nevada - 26.11.06

The CABARET star was shocked by Hudson's appearance when she invited the late actor and Taylor to a concert and then met the stars backstage.

She realised that his look was similar to that of gay friends of hers in New York - and revealed her shock to Taylor, who has since become a leading HIV and AIDS activist.

Minnelli recalls, "I hadn't seen him (Hudson) in a long time... (and) he looked different. I thought that he looked like just a couple of friends that I had seen lately in New York, who had this new disease.

"I said to Elizabeth, 'There is something called AIDS, and I don't know, but I think Rock may have it.' She said, 'He looks ghastly, what is it?'

"I explained it to her as much as I knew and she said, 'We have to do something."

Source: WENN