Rudy Giuliani was rushed to emergency surgery on Sunday after his right leg gave way on the first day of his vacation on Long Island.

Talking about his quadriceps tendon surgery, the former mayor exclusively told Page Six from his hospital bed, “I was a catcher from a very young age, and I have suffered with ‘catcher’s knee’ for years, and the doctors said it would deteriorate.”

“Then my knee gave way when I was walking on Sunday . . . I tried to get up but [my wife] Judith ordered me not to move. If it hadn’t been for her, the injury would have been a lot worse. I now call her ‘Nurse Nancy.’ I swear to God, it was my first day of vacation and we’d planned to play a lot of golf. I don’t think I will be playing golf for a few weeks. But I am already up and limping around. I’m a tough guy, so this isn’t going to stop me.”

Giuliani fell as he and Judith hosted a barbecue for friends, including Somers and Jonathan Farkas and Joanne and Roberto de Guardiola, at their Long Island home.

Judith told Page Six, “It is a good thing that I am a trained nurse, because when he fell, I saw his leg had fallen in an unnatural way. Our guests wanted to pick him up — he’s a tough guy and he wanted to get up — and I said he should not move. It was an instant red flag. When I looked at the limb, I knew if he got up, it would just do more damage.”

She added, “Rudy had to have surgery right away . . . He will be in the hospital for a few more days, but he’s in great spirits. He keeps calling me ‘Nurse Nancy.’ He is the eternal optimist. He may have to use crutches for a while.”

But “of course, he’s already working from his hospital bed, he’s got the computers going, two phones, a couple of iPads and a Kindle. He’s not by any means down for the count.”