VIENNA, Austria - She could have danced all night. Instead, she stifled yawns.

Paris Hilton poses for photographers during the traditional opera ball in Vienna February 15, 2007. [Reuters]

Hotel heiress/reality TV star Paris Hilton certainly didn't look like she was having a ball Thursday night at the Vienna Opera Ball, Austria's society event of the year.

Live TV coverage repeatedly showed her looking bored as she sat in her luxury box at the State Opera House.

As debutantes in white dresses and their escorts in black tuxedos and tails marched into the ornate ballroom, Hilton was seen resting her head in her hands, absentmindedly flipping through the program and fiddling with her mobile phone.

"Look how excited she is," deadpanned a commentator for public television station ORF, which broadcast the ball live.

Hilton was the guest of Richard Lugner, a 74-year-old married construction magnate who invites a celebrity each year. His previous guests have included Geri Halliwell, Pamela Anderson and Carmen Electra.

The annual Opera Ball draws about 4,500 well-heeled Austrian and foreign celebrities, dignitaries and socialites. Tickets often sell out months in advance.

On Friday, Hilton was heading to the Tyrolean ski resort of Ischgl to celebrate her 26th birthday. Her birthday is Saturday.

The festivities in Ischgl included a Paris Hilton look-a-like contest and the "Paris Life Show" - photos of her growing up. Hilton planned to shed a white coat to symbolize the passing of another year, organizers said.