Melbourne, July 26 : Beyonce Knowles has been left so confused by her gruelling world tour schedule that she even forgets where she is.

Just over three months into her tour, the singer was recently unable to tell exactly where she was in America.

She could only say that she was in an American city beginning with the letter S, but she was not sure which one.

"Where am I?'''''''' the Daily Telegraph quoted Knowles as saying, when asked by Insider, before hitting the stage for the 51st show of her 87-date world tour..

"I''''m in San Francisco, I think. No, San Diego? Oh, Sacramento.

"That''''s terrible. I just got here, just got off of the bus, so I haven''''t seen anything but the venue,'''''''' she added.

Her world tour is one of the biggest ever, having grossed more than 37.5 million dollars in ticket sales so far.

She''''s due in Australia in September to play seven shows, booking two performances at Sydney''''s Acer Arena on September 18 and 19. (ANI)