Roger Federer [Images], revelling in the unusual role of being the underdog, will continue his bid for a fifth successive US Open [Images] title on Friday when he plays little-known Brazilian Thiago Alves in the second round.

The Swiss, relegated to second seed in New York after losing his number one ranking to Spaniard Rafael Nadal [Images], is trying to avoid ending the year without a Grand Slam title for the first time since 2002.

Having lost to Nadal in both the French Open and Wimbledon [Images] finals, Federer is a rare underdog, something the crowd appears to be responding to.

"The change I feel is fans are really supporting me and telling me I'm still number one and the best -- 'you're going to be there again' and stuff," Federer said.

"So I feel like I've got unbelievable support from the fans watching me and seeing people in the streets and stuff. It's really nice."

Third seed Novak Djokovic [Images], runner-up to Federer last year, faces American Robbie Kendrick in the second round.

Former champions Andy Roddick [Images] and Marat Safin [Images] are also in action. Eighth seed Roddick takes on Latvian teenager Ernests Gulbis, while Russian Safin plays 15th seed Tommy Robredo of Spain.

In the women's event, second seed Jelena Jankovic, one of five players who could be ranked number one at the end of the tournament, plays China's Zheng Jie in a third-round match.

Olympic [Images] champion Elena Dementieva and former champion Lindsay Davenport [Images] are also in third-round action.

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