Anna Wintour swaps fashion for Flushing Meadows

The devil wears Nike! Now we know what drove Roger Federer to thrash Andy Murray in double-quick time in the US Open final last night - he had to finish quickly so that his number one fan, Anna Wintour, could leave Flushing Meadows in time to get back to New York Fashion Week and the Marc Jacobs show.

Although the US Open coincides with Fashion Week, the city's fashionistas are not known for their knowledge of the game. But La Wintour, editor of American Vogue and recently voted again the most powerful woman in New York fashion, is a huge fan of the elegant Swiss champion. She was at Flushing Meadows on Saturday (above with her partner, Shelby Bryan) to see him beat Novak Djokovic in the semi-finals and she was back for yesterday's final, sitting right behind Mrs Roger Federer.

The final should have been played on Sunday night, but because of the rain delays over the weekend, the match clashed with the Proenza Schouler show, one of her favourites. Never mind - it seems Roger comes first.

This is not the first time Wintour has gone out of her way to follow Federer's fortunes. Earlier this summer she flew into London to watch him beat Frenchman Marc Gicquel in the third round of Wimbledon.

Those used to seeing her steely expression in the front row of fashion shows from New York to Milan are taken aback to see her smiling and clapping. As one New York fashionista blogged in the small hours: "She's always looked so bored and stern at every fashion show and to see her so pleasantly engaged and alive, well, it made me think that perhaps she should start working towards traveling the tennis circuit.

"The only other time I have seen her smile is when she was with Roger Federer at the Oscar de la Renta show [last year]."