"I describe it as the luckiest day of my life," Rodriguez responds when asked about how they met, which is met by a chorus of "Awws" from the crowd.
He claims that he was leaving a meeting in Los Angeles and couldn't find his car when someone tapped him on the shoulder.
"Someone taps me on the shoulder, and I turn around and I do not recognize this person. And it's Jennifer, but she's dressed up as Harlee from Shades of Blue and she's in her jeans and her big boots. And it took me about 4 or 5 seconds," he told DeGeneres. "It's Jennifer. 'Oh my God, Jennifer, you look beautiful.' I was so embarrassed and then I got a little nervous."
"And she says, 'You have my number, reach out,'" he continued. "And I went home that night and reached out."
Degeneres, however, was (jokingly) skeptical.
"She says you went up to her and you approached her at her table and started talking," she said.
"Oh my god, no," Rodriguez responded.
"One of you is lying," DeGeneres joked.
Later, DeGeneres had Rodriguez Facetime Lopez, and so she could continue her tongue-in-cheek interrogation.
"Hey you know, He just told a totally different story. He said that you went up to him and not the way you told it," she said.
"No. I went up to him and tapped him on the shoulder," Lopez said.
"We'll look at the tape, I don't know," DeGeneres concluded.
The full segment airs Monday on The Ellen DeGeneres Show.
For more about A-Rod and J-Lo, watch the video below.