First up, Lea Michele and Chris Colfer in the best duet in the episode "Duets". I still wouldn't call myself a fan of Kurt, but this is lovely.
Then there's the absolutely resplendent Audra McDonald teaming up with Patti Lupone. I don't care for Patti, but Audra is amazing and they song brilliant together.
And of course, the iconic original - Barbra and Judy.
Okay, as you were (Good morning).