Isner serves the USA into Davis Cup quarterfinals with 3-1 win over Australia

The United States has on Sunday secured its place in the quarterfinals of the Davis Cup with a 3-1 win against Australia, after John Isner fought off a late challenge from Bernard Tomic to win 6-4, 6-4, 5-7, 7-6 in Melbourne.

After cruising through the first two sets with ease, the big-serving American had silenced the crowd and looked to put the rubber away in straight sets, but a resilient and injured Tomic battled his way through the third, and took a rare break point opportunity to extend the match.

With the momentum on Tomic's side, he was clinical on serve in the fourth, but eventually lost an entertaining fourth set tiebreaker to a clinically-serving Isner, who hit 49 aces in his dominant performance.

The win wrapped up a 3-1 victory in the tie for the USA, which will host the winner of Croatia and Belgium in July, and team captain Jim Courier said it was important to get the win playing away from home, and praised Isner's "breathtaking" performance on serve.

"We knew it was going to be difficult," Courier told the crowd following the tie win, "But our team certainly came good, and John especially stepped up so big."

The American was automatic on serve early in the rubber, not giving Tomic - or the Australian crowd - a chance to get going. Frustrations were clearly on display from the Australian camp; after the first two sets, which Isner wrapped up in an hour, Tomic had only won five points on the American's serve.

Despite the dominance however, Tomic was able to keep himself in the match heading deep into the third. While he was holding serve nervously at times, Isner was holding with ease, until Tomic went up 6-5 in the set and was presented with just his first break point for the entire match.

Isner would go on to save five break points, however Tomic managed to scrap long enough for Isner to tire and hit a couple of uncharacteristic unforced errors - allowing the Australian to commit robbery in taking the set and keeping the rubber alive.

From there, the momentum seemed to shift and Tomic managed to kick up a gear. After receiving a medical timeout for his troublesome wrist and looking slow and lethargic around the court, the 23-year-old was moving swiftly and working the angles, and reversed the service fortunes to not allow Isner a sniff during his service games.

After the pair forced a do-or-die tiebreak for the Australian team, Isner once again found his automatic serve, and crunched a number of easy aces to deny the Australian and the parochial crowd a shot at a deciding fifth set.

Isner, the world No. 11, said wrapping up the tie in four matches was a great relief for team USA.

"We've been here for a while practicing. We prepared well and it showed out here it was an incredible tie, we knew it would be very, very tough against Australia," Isner said after the match.

Meanwhile Australian captain Lleyton Hewitt said the Australian team, missing arguably two of its top three players in Nick Kyrgios and Thanasi Kokkinakis, struggled to settle.

"It was obviously pretty tough at times, with the late changes," Hewitt told the press on Sunday.

"We tried to give ourselves the best opportunities to take it to a fifth match."

The quarterfinals of the Davis Cup are to be held from July 15 until July 17, with the USA to host either Belgium or Croatia at a location in the US to be decided. Endit