The 'Lose You To Love Me' singer is a 'Friends' super-fan and has been close pals with Jennifer, who played waitress Rachel Green in the sitcom, for several years but she readily admits she completely "freaked out" when they first spoke to one other in the restroom at a celebrity party.
Speaking to the 50-year-old actress on 'The Ellen DeGenres Show' - which Jennifer guest hosted on Friday (24.01.20) - Selena recalled: "Nobody knew who I was and you were in the bathroom wearing a black dress. I think we were at a Vanity Fair [party] or something event. My heart stopped and I freaked out."
The 27-year-old pop star also opened up about releasing her deeply personal and honest album 'Rare' recently, and it's only in her adult life that she's learnt that being "vulnerable" isn't a "weakness".
She said: "When I was younger I felt like it was a weakness to be vulnerable and to share my heart with people.
"I realised that everybody else seemed to be narrating my life for me, so why don't I put something out that is my side of the story?
"It's not hateful or anything, it's simply a beautiful moment to let go of."
The 'Wolves' hitmaker previously admitted she feels "very lucky" to be friends with 'The Morning Show' actress because she is so "kind and warm" and helps to guide her through life.
She said: "I met Jennifer through my management company - we're represented by the same people - and she's been so wonderful to me. She's invited me over to her house and made pizza for me and just been so kind and warm.
"I'm very lucky to have her as a friend and we've talked a lot about dealing with the media attention and having your life exposed at times. I know I can call her for advice and that's a nice feeling."