The star has been holed up in a West London studio rehearsing for the gig, and yesterday she revealed that she she'll be performing seven new songs. One of which has the saucy name of 'Sex Dreams' and contains some quite rude lyrics.
Taking a break from rehearsals Gaga greeted some of her waiting fans - while wearing a pig's nose. What else?!
But unlike many of her other outfit choices, there was a reason behind this one - another of her new songs is called 'Swine' and features the lyrics: 'You just a pig inside a human body. Screw out you just disgusting. You just a pig inside...SWINE.' Nice!
Yesterday evening, her outfit of choice consisted of a black and white leotard and black mouse ears. The look was completed with a long black wig and very high platform boots.
The 'Poker Face' singer said she is relieved to be back performing after having time out following hip surgery earlier this year.
She told The Sun: "I came to the UK because I love performing here.
"I am just relieved to be back and playing new music. I spent a fortune on rehearsals because I want things to be right come the big night. The Roundhouse is a famous venue and I want to make it special for the fans."
Watch Gaga's latest music video for 'Applause' below: