Isner delivers fastest serve in history to spearhead U.S. victory

John Isner plays a backhand against Bernard Tomic in the Davis Cup World Group tie between Australia and the U.S. at Kooyong. Robert Prezioso/Getty Images

KOOYONG -- John Isner produced a "breathtaking" all-round display to guide the U.S. to victory in their Davis Cup World Group first-round tie against Australia.

The world No. 11 withstood a belated charge from Australia's Bernard Tomic at Melbourne's historic Kooyong, prevailing 6-4, 6-4, 5-7, 7-6 (7-4) to give the U.S. a 3-1 victory that wrapped up the best-of-five tie to progress to a home quarterfinal tie against Croatia or Belgium in July.

U.S. captain Jim Courier described the result as "massive" after what he described as "tough couple of years for us" in reference to World Group defeats by Great Britain in 2014 and 2015. "This was a touch match-up on paper and it was a tough match-up in reality. For us to get to the second round is a big deal."

Australia needed Tomic at his best if they were to avoid losing to the U.S. on home soil for the first time since 1982, but the world No. 20 initially had no answers against his red-hot opponent.

Fresh from a dominant straight-set victory over Sam Groth on Friday, Isner was again in scintillating form. His serve, of course, is always a major weapon, and his 49 aces against Tomic featured the fastest in ATP Tour and Davis Cup history at 157 mph (253 km/h), usurping the 156 mph bullet fired by Ivo Karlovic on Davis Cup duty for Croatia in 2011; but his groundstrokes, volleying and court craft were also too much for Tomic early.

In front of a passionate home crowd, Tomic - who had a medical time-out after dropping his serve in the seventh game of the second set - struggled with his movement and body language through the first two sets before finally finding some fight in the third.

Tomic claimed the set on his fifth break point of an epic game, bringing the previously subdued crowd to its feet, and he continued his fight in the fourth only to come up short against Isner, who, fittingly, claimed the match with two enormous serves. Tomic previously had lost only three of 19 Davis Cup singles.

Courier described Isner's performance as "breathtaking", saying "he stepped up big for us, he's done it for us in Davis Cup before and he's done it again today."

John Isner said: "The first two sets went really well but I knew, being Davis Cup and the crowd on his side, he was going to make a push, and he did in the third set, but ... I was serving really well and was able to close it out in four."

On Saturday, U.S brothers Mike and Bob Bryan defeated Lleyton Hewitt and John Peers after Friday's singles matches - between Isner and Groth, and Tomic and Jack Sock - were split.

The tie was the 46th between Australia and the U.S, the first since the 1999 quarterfinals. The U.S. has been crowned Davis Cup champions on 32 occasions, with Australia second with 28.