Nick Kyrgios finished off John Isner with his 20th ace to give Australia a 2-0 lead over the United States in their Davis Cup quarterfinal on Friday.
Kyrgios won 7-5, 7-6 (5), 7-6 (5) after Jordan Thompson upset Jack Sock 6-3, 3-6, 7-6 (4), 6-4 on a hard court at Pat Rafter Arena.
Australia can clinch the tie and advance to a semifinal in September against Italy or Belgium with a win on Saturday in doubles. Sam Groth and John Peers are scheduled to play the American pair of Sam Querrey and Steve Johnson.
"Hopefully we can close it out tomorrow, it's been an unbelievable day," Kyrgios said. "He's one of the best servers in the world, a proven player. I've been putting my head down and I returned really well."
Isner said he ran into an in-form player.
"I felt like I played well enough to beat anyone out there, but not Nick," Isner said. "He came up clutch."
Kyrgios came from a break down in the first set, broke Isner to love in the 11th game, and clinched the set on an ace. In the second, Isner saved two break points at 5-5 and Kyrgios won the last three points.
In the third, Isner saved a match point serving at 5-6 and lost the last three points again.
The 79th-ranked Thompson won both of his singles in his Davis Cup debut against the Czech Republic in February, but he was more impressive against No. 15 Sock, the highest-ranked player in the quarterfinal. Sock looked out of sorts at times and served two double faults to hand Thompson his first break at 5-3.
The American rallied to win the second set, then recovered from 4-1 down to level the third set before Thompson won it in a tiebreaker.
Thompson clinched the match in the fourth set by breaking Sock's service twice.
France lead Britain 2-0
ROUEN (FRANCE): lucas Pouille and Jeremy Chardy won their matches in straight sets to give France a 2-0 lead over Britain in the Davis Cup quarterfinals on Friday.
After Pouille beat Kyle Edmund 7-5, 7-6 (6), 6-3, Chardy followed up by swatting aside Dan Evans 6-2, 6-3, 6-3 on indoor clay. France only needs to win Saturday's doubles match to reach the semifinals.
The 17th-ranked Pouille is France's top player in the absence of No. 10 Jo-Wilfried Tsonga and No. 11 Gael Monfils, while No. 22 Richard Gasquet is also out.
Edmund, ranked 47th, was filling in for top-ranked Andy Murray, who's nursing an elbow injury.
Edmund was leading 5-2 in the second-set tiebreaker before losing four straight points.
Pouille broke Edmund's serve four times overall, dropping his own twice. Chardy sealed victory by breaking Evans' serve again, clinching the win when Evans could only return his strong forehand pass into the net.
Serbia lead Spain 2-0 as Djokovic returns
BElGRADE: Novak Djokovic and Viktor Troicki won their singles matches in straight sets to give Serbia a 2-0 lead against Spain in the Davis Cup quarterfinals on Friday.
Djokovic beat Albert Ramos Vinolas 6-3, 6-4, 6-2 and Troicki followed up to win 6-3, 6-4, 6-3 against Pablo Carreno Busta on an indoor hard court in Belgrade.
Serbia needs a doubles victory on Saturday to reach the semifinals for the third time. Troicki will be back on court to team up with 40-year-old Nenad Zimonjic.