TASHKENT, Uzbekistan (AP) Jack Sock clinched the United States' Davis Cup World Group playoff win over Uzbekistan with a four-set victory over Denis Istomin on Sunday.
Sock, ranked No. 29, struggled at times on the clay surface in the Central Asian nation, but held his nerve in a wild fourth set to win 6-2, 2-6, 6-4, 6-4 against Istomin, who is ranked 33 places below him.
It was Sock's second win of his debut weekend in an inexperienced Davis Cup team also containing debutant Steve Johnson.
''Closing out a tie is never easy, even for a veteran. For Jack to come through in his debut was very impressive,'' U.S. captain Jim Courier said. ''One of the challenges here was bringing a team with very little experience, but one of the great things as we come out of this tie is now these guys have had a taste of Davis Cup. We have more options at our disposal.''
With Sock serving for the match at 5-4 in the fourth set, he saved four break points from Istomin, then saw two match points saved before finally closing out the win.
Sock's victory gave the U.S. an unassailable 3-1 lead over Uzbekistan and completes a comeback from 1-0 down on Friday.
The fifth rubber later Sunday had been due to pit world No. 47 Steve Johnson against 158th-ranked Uzbek Farrukh Dustov, but was not played after Sock's win over Istomin secured the U.S. win.
The U.S. has played in the World Group every year since 1989, while Uzbekistan never played in the top tier and has now lost at the playoff stage four times in the last seven years.