Daniella Francesca claimed to The Sun that she met the 25-year-old at the Bar 32 nightclub in Brighton last month before going home with him in a taxi in the small hours.
In pictures posted to Twitter the following morning, a sleeping Duffy was seen naked in bed alongside the caption "When Shane Duffy doesn't want to go home."
"I was with a group of pals for my mate's 30th birthday. We were on a big table and then some blokes came and sat down next to us," Francesca told the newspaper. "Shane was there with lots of his Irish friends. They had a lot of drinks and were having a great time.
"I was sitting next to Shane and we were talking. I asked him what he does for a living. He said, 'I'm Shane Duffy' and paused. I looked at him blankly. He then made me get my phone out and put his name into Google. He was looking at me in disbelief that I didn't know who he was.
"He took my phone, took a few selfies of us, and captioned them with his name on and made it my Snapchat story."
Francesca, who claims to have more explicit pictures of Duffy on her phone, alleged that Duffy's partner Catherine Carlin - mother of their two children - then contacted her to confront her over the pictures.