The Pretty Woman actor met the Twilight heartthrob at a party honouring the 63-year-old's new movie Arbitrage, and Richard confessed he had "no idea" R-Patz was such a big name until his wife Carey Lowell started quizzing him about their meeting.
He told E! News: "He was a perfectly nice guy, but I had no idea!
"But I was getting calls from my wife going, 'What are you doing with him? He's so cute, but what are you doing with him?'."
Richard and Robert were snapped together at the event in Los Angeles, with the 26-year-old British actor sporting a black T-shirt, black coat and black trousers.