UPDATE: The USA have emerged victorious in their opening Hopman Cup tie at Perth Arena today, defeating South Africa 2-1.

John Isner and Venus Williams went into the mixed-doubles decider determined to prove their worth as second-seeds, eventually proving too good for Kevin Anderson and Chanelle Scheepers.

Williams’ tenacity combined with Isner’s serving prowess saw them take the deciding rubber 6-3 6-2.

After a strong start to the tie by Williams, South Africa’s Anderson stunned the favourites with a grinding win over world No.14 Isner.

Anderson, 203cm, went toe-to-toe with the 206cm American all match before stepping up his game in the tiebreakers to run out with a 7-6 (7-0) 7-6 (7-5) win.

Neither managed to break the other’s serve as the Perth Arena crowd lapped up the closest match seen at the tournament so far this year.

Earlier Williams shrugged off a challenge by Scheepers to record a 4-6 6-2 6-3 win and give second-seed USA the perfect start to the tie.