Last fall, Lady Gaga and Bradley Cooper stole the hearts — and tears — of audiences around the world with their performance in "A Star is Born." Years before they took the stage to sing "Shallow," Barbra Streisand and Kris Kristofferson starred in the 1976 iteration of the film and this week they reunited to sing a special duet from the beloved movie.

Streisand was playing to a sold-out show in London's Hyde Park as part of the British Summer Time festival Sunday when she welcomed her former co-star to the stage. Kristofferson was among a slew of special guests, including Bryan Ferry, Ramin Karimloo, The Kingdom Choir and Richard Marx.

"One of my favorite leading men, Kris Kristofferson," Streisand said, as the actor walked out. The pair hugged as they walked to the center of the stage.

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"Here's a song that we sang together, in the movie, right?" Streisand said as music began to play, "Oh, I love this song." The stars then launched into a rendition of the beloved duet "Lost Inside of You."

Streisand teased the reunion on Instagram in April, posting an image of the pair with the caption,"It was so wonderful to see my friend Kris who stopped by yesterday. Stay tuned ..."

The icon starred in the 1976 film, as lead Esther Hoffman beside Kristofferson's John Norman Howard. She won an Oscar for best original song — alongside Paul Williams — for the love song "Evergreen" in the film. The star also performed "Evergreen" during her concert in Hyde Park.

When asked if she had seen the full cut of the 2018 remake shortly before it was released, the actress told Billboard,"I haven't seen the full cut, but it's very good. Every time that film is made it's a success. I loved Judy Garland's version, I like this one a lot, and I liked mine." The movie has been re-made four times, beginning with the 1937 version starring Janet Gaynor and Fredric March.

The 2018 "A Star Is Born" was one of the highest grossing films of the year, earning nearly $200 million at the box office. The film's hit "Shallow" also won the Academy Award for best original song.