ATP World Tour Finals: Novak Djokovic caps his best season with title triumph

    By Paul Gittings, CNN

    Updated 2224 GMT (0624 HKT) November 22, 2015

    Novak Djokovic of Serbia lifts the trophy after beating Switzerland's Roger Federer of Switzerland in the final of the ATP World Tour Finals.
    Photos: Fourth straight for Djokovic
    Novak Djokovic of Serbia lifts the trophy after beating Switzerland's Roger Federer of Switzerland in the final of the ATP World Tour Finals.
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    Djokovic and runner up Federer of Switzerland pose with their trophies following the final at the O2 Arena.
    Photos: Fourth straight for Djokovic
    Djokovic and runner up Federer of Switzerland pose with their trophies following the final at the O2 Arena.
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