Brooklyn Decker: Officers Carrying Automatic Weapons at U.S. Open

Model-turned-actress Brooklyn Decker witnessed a distinct change of mood at tennis' U.S. Open on Friday compared to previous days. The Just Go With It star -- whose husband, Andy Roddick, was playing Rafael Nadal in a quarterfinal match -- said that security was visibly beefed up as the 10th anniversary of the 9/11 attacks approached.

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Decker tweeted Friday, "A bit of a shift in mood at the Open today... Officers in helmets carrying fully automatic weapons. Good to see they're taking precaution."

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Security may also have been increased because of the presence of first lady Michelle Obama, who watched the game with Billie Jean King from a private box.

Decker and Roddick tied the knot in April 2009. On Friday, he lost to Nadal in three straight sets.

The night before the match, Decker was among the attendees at Justin Bieber's Fashion's Night Out party, a fundraiser for Bieber's main charity Pencils of Promise. The event raised enough money to build a school, according to the singer's manager Scooter Braun.

Vogue editor Anna Wintour, Gossip Girl's Chace Crawford, Tyson Beckford, Usher, Eddie Cibrian and LeAnn Rimes were also at the event, which was co-sponsored by Dolce and Gabbana.