CANBERRA, Jan. 5 (Xinhua) -- Australian tennis star Lleyton Hewitt defeated John Isner in straight sets to give his country victory in the Hopman Cup tie against the United States in Perth on Tuesday.

    Hewitt beat the tall American 6-1, 7-5 in 75 minutes after compatriot Sam Stosur cruised past Melanie Oudin 6-2, 6-4 in 67 minutes earlier in the day.

    World number 22 Hewitt dominated the opening set as Isner's booming serve abandoned him.

    He broke Isner twice to race out to a 5-0 lead in 16 minutes before the American finally held serve but Hewitt went on to claim the first set in 26 minutes.

    Isner found his rhythm in the second set but Hewitt snared the crucial break in the 11th game on the way to the comprehensive win.

    "I played extremely well," Hewitt said.

    "John's always going to be an awkward player for anyone.

    "I returned extremely well, made him play a lot of balls out there and really stepped up my game."

    Australia's victory keeps its title hopes alive, but American hopes are dashed after losing its opening two ties.