Pippa Middleton at U.S. Open

Tennis fan Pippa Middleton was spotted in New York today as she attended day nine of the U.S. Open as a guest of Roger Federer.

Wearing a colour block dress, accessorised with tan wedges, a straw handbag and vintage sunglasses,  she stopped to pose for photographers before entering the venue at Flushing Meadows, Queens.

Once inside the courts she took a seat next to dark-haired Spencer Vegosen - a Harvard graduate and tennis player - before watching the women's singles quarterfinals game.

Mr Vegosen, who now resides in New York but is originally from Illinois, Chicago,  is a familiar face on the sporting scene and he was once one of the top junior tennis players in the U.S.    Mr Vegosen received a BA in East Asian studies and mathematics from Harvard University and spent last summer working as an analyst for Goldman Sachs in Hong Kong.

"She was only there for a short time",  a source told the paper, adding they were there with Mazdack Rassi, owner of photography company Milk Studios.  Her trip, during which she is apparently courting the perks of fame, come despite her demands to remain out of the public gaze.  Newspapers have respected her request to be recognised as a private citizen, she still very much seems to be enjoying the high-flying life of a socialite.

Pippa, who turns 29 on Thursday, is in town for meetings over her new book, which is out on October 30. She will not be holding an publicity events for the book while she is here. Billed as a "comprehensive seasonal guide to simple and creative entertaining", it is a book she hopes will cement her credentials as a party planner, and industry observers believe it could net her a small fortune in the process.

It is believed that Pippa is set to make an appearance at New York's Fashion Week, which kicks off on September 6.