BRISBANE, Australia (AP) Jordan Thompson continued an unbeaten start to his Davis Cup tennis career, upsetting American Jack Sock 6-3, 3-6, 7-6 (4), 6-4 on Friday to give Australia a 1-0 lead in their World Group quarterfinal.
Thompson won both singles in his Davis Cup debut against the Czech Republic in February, and the 79th-ranked Australian continued that form over No. 15 Sock, the highest-ranked player in the tie.
On an outdoor hard court at Pat Rafter Arena, Sock looked out of sorts at times and served two double faults to hand the 22-year-old Thompson his first break at 5-3 in the opening set.
The American rallied to win the second set, then recovered from 4-1 down to level the third set before Thompson won in a tiebreaker. The Australian clinched the match in the fourth set by breaking Sock's service twice.
No. 16-ranked Nick Kyrgios of Australia played John Isner in the second singles match later Friday.
The winner will play Italy or Belgium in the semifinals in September.
The U.S. leads the head-to-head series 26-20 and won the most recent meeting between the teams last year on grass at Kooyong in Melbourne in the first round.
