John Isner battles back to take five-set thriller against Frances Tiafoe

John Isner has produced a stunning comeback to battle from two sets down and overcome wildcard entry Frances Tiafoe in the opening round of the US Open.

The 31-year-old beat his American compatriot 3-6 4-6 7-6(5) 6-2 7-3(3) to progress through at Flushing Meadows in New York.

Two breaks of serve in the opening set gave Tiafoe an early foothold on the match, and he held throughout the second to leave his opponent on the brink of an early exit.

A tight third set would prove to be pivotal, however, as Isner dug deep to edge a tie-break and keep his hopes just about alive on home soil.

The final two sets then went the way of the 2011 quarter-finalist as he completed his comeback, taking the decider with another tie-break after being pushed all the way by Tiafoe in a real opening-round thriller.