MELBOURNE, AUSTRALIA - MARCH 04: Sam Groth of Australia plays a forehand volley in his match against John Isner of the United States during the Davis Cup tie between Australia and the United States at Kooyong on March 4, 2016 in Melbourne, Australia. (Photo by Quinn Rooney/Getty Images)

John Isner has given the USA a 1-0 lead over Australia with a straight sets win over Sam Groth in the opening match of their Davis Cup tie at Kooyong.

The big serving pair went blow for blow in the opening set, with Groth taking it right up to the world No.11. Groth had three break points midway through the first set, but failed to capitalise, with Isner eventually winning the opening set in a tiebreak.

Isner then proved far too good for the Australian in the final two sets, completing a 7-6, 6-2, 6-2 win.

Australian No.1 Bernard now takes to the court against World No.24 Jack Sock to try to level the tie for the Australians.