Pippa Middleton With Andre Balazs and Sean Avery in New York

Pippa Middleton, the Duchess of Cambridge's little sister, made international headlines during her trip to the U.S. this week.

First, the 28-year-old spent time with wealthy hotel owner Andre Balazs at his resort in the Hamptons, Shelter Island.

An onlooker claimed that there was "definite chemistry between the pair," according to The New York Post. The insider also referred to the duo's exchange as "flirt central."

Balazs, 55, owns eight luxury hotels across the U.S. including Los Angeles' Chateau Marmont and The Mercer in New York.

Middleton then traveled via luxury seaplane to New York City, where she dined at some of the city's top restaurants.

Later during the same evening, Middleton was spotted in New York's Meatpacking District at the Dream Downtown hotel. In the venue's Electric Room, the famous bachelorette chatted with former New York Ranger Sean Avery, according to New York Daily News.

Middleton and friends stayed at New York's Upper East Side luxury hotel, the Carlyle.

Also during her trip, Middleton attended to the U.S. Open on Tuesday. The younger sister of Catherine, Duchess of Cambridge, she donned a figure-hugging colorful dress paired with a Kate Spade bag, sunglasses, and tan wedges.

Unlike her sister who is known to recycle dresses, Pippa tends to wear bolder fashions and has never been photographed in the same outfit twice.

The style icon will celebrate her 29th birthday on Thursday. It is believed that Duchess Kate's little sister may attend New York Fashion Week, which kicked off on Monday.

The New York vacation is said to be for both business and pleasure for Middleton, who has a new book coming out in October: "'Celebrate' A Year of Festivities for Families and Friends." Ahead of its release, Middleton has scheduled meetings and promotional public events in the Big Apple.

Middleton's vacation was far different from Prince Harry's notorious stay in Las Vegas last month where he was photographed drinking heavily and partying at the Wynn Hotel.