Lady Gaga made a surprise appearance at a bar in New York last night (September 29).

The singer mingled with fellow drinkers at The Oak Room bar and restaurant inside The Plaza Hotel.

Wearing a long blonde wig and revealing outfit, Lady Gaga made a brief appearance on stage.

Her visit was kept secret until it was revealed on The Oak Room's Twitter page.

“Lady Gaga here tonight. Maybe we'll get a serenade in The Oak Bar tonight,” a message said.

And in a message on her own Twitter page, Lady Gaga said: “Lonelydreams+champagne streams,plaza courtyards, I can't swim among them, so ill drinkinstead a star.”

It is the first time Lady Gaga has appeared in public since the death of her grandfather last week. Joseph Germanotta, 88, passed away at a nursing home in New Jersey.

Meanwhile, Lady Gaga is scheduled to resume the latest North American leg of her Monster Ball world tour in Los Angeles on October 2.

(by Jason Gregory)