Fans moved by sound of Gaga's music
Screen queen Dame Julie Andrews joined music star Lady Gaga on stage to celebrate the 50th anniversary of family favourite The Sound Of Music.
After a clip of the movie, Gaga appeared in a floaty white dress to perform a medley featuring The Sound Of Music, My Favourite Things, Edelweiss and Climb Every Mountain - to an overwhelmingly positive reaction on social media.
Dame Julie then appeared and was given an emotional welcome from the Poker Face singer, before recalling her "glorious" memories of making the 1965 classic film.
She said: "Dear Lady Gaga, thank you for that wonderful tribute. Oh my God. It really warmed my heart, it really did.
"It's hard to believe that 50 years have gone by since that glorious film was released. I blinked and suddenly here I am.
"I think that I do speak for everyone connected with the movie when I say we all really felt blessed to have been a part of it and as for me, well, how lucky can a girl get?
"Great music does more than enhance a film, it cements our memories in the film-going experience."
Dame Julie presented the award for original score to Alexandre Desplat for The Grand Budapest Hotel.
Lady Gaga, who is known for her unusual performances, was visibly moved on greeting Dame Julie.
Twitter went "gaga", as one user put it, with many admitting they had been brought to tears.
Actor Steve Martin tweeted: "Congratulations to Lady Gaga and Julie Andrews for a most emotional moment on this year's Oscars. Oops, forgot to be satirical."
One person named Anahita Joshi said: " What an awesome tribute! I sang along, I cried, I loved it!"
Another tweeting under the handle @KISAreads said: " Might have gotten choked up when Julie Andrews hugged Lady Gaga. Two of my heroes in voice and character. I love them both."
Others joked that Dame Julie should return the tribute by singing one of Gaga's hits, Bad Romance.
Adam Oliver tweeted: " If Julie Andrews had followed that with a cover of Bad Romance, the internet would have exploded."
Dame Julie's phrase "Dear Lady Gaga" was trending on the site following the performance.