Perth:The United States capitalised on Jelena Jankovic's injury misfortune to beat Serbia 2-1 in the final and win their fourth Hopman Cup in six years.
Aided by a one match headstart in the final after Jankovic, battling a right thigh injury, forfeited her singles match, Serena Williams and Mardy Fish claimed the title with a straight sets win in the deciding mixed doubles clash, 7-6 (7/5), 6-2.
That win came after Novak Djokovic had levelled the tie with a three-set win over a brave Fish in the men's singles, 6-2, 6-7 (4/7) 7-6 (7/4).
For the third day in a row a hobbling Jankovic played in a deciding mixed doubles rubber with heavy strapping on her injured right leg, but it was third time unlucky for her and
Djokovic as they squandered a good start and succumbed to the Americans.
The Serbs looked on track for an upset win when they raced to a 4-1 lead in the first set, but the superior fitness of the Americans started to tell and they worked their way back into the contest.
Djokovic and Jankovic, who is ranked number three in the world, were clearly feeling the effects of their third tie in as many days and the Americans took the first set on a tie-break and then dominated the second set.
Fish sealed the victory with a backhand pass to break the Jankovic serve and end the match after one hour, 25 minutes.
It was the United States' fifth win here overall and Fish's first Hopman Cup success, while Williams teamed up with James Blake to win the title in 2003.
In her two appearances here, Williams is yet to play in a losing rubber.
With Djokovic needing to win to keep the final alive, he and Fish played a marathon singles match that lasted for two hours and 35 minutes.
The world number three started well, breaking the normally tricky Fish serve twice in the first set.
However, the 39th-ranked Fish saved a match point in the second set and then levelled the match in a tie-break.
For much of a tense third set, Fish seemed to have the edge over a listless Djokovic, who was battling a sore right shoulder and was struggling to keep his mind on the job in his
fifth match in three days.
In the 10th game of the set, Fish threatened to break the Djokovic serve and claim the match, but the Serb hung on and forced a tie-break.
Fish showed signs of fatigue in the tie-break and played several loose shots on his forehand side, allowing Djokovic to steady and pull off a hard-earned win.