Elvis Presley fell for one of Frank Sinatra's secret girlfriends when he discovered what she could do in bed.

The King of rock 'n' roll was smitten with South African dancer JULIET PROWSE when they worked together on the movie G.I. BLUES and couldn't stop boasting about her bedroom skills to his buddies.

BYRON RAPHAEL, who was hired by Presley to wrangle girls for one-night stands, recalls, "He bragged to his friends that Prowse liked to grab her ankles and spread her legs wide during the act (of sex)."