TASHKENT, Uzbekistan (AP) -- Jack Sock clinched the United States' Davis Cup World Group 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 topsy-turvy fourth set to win 6-2, 2-6, 6-4, 6-4 against Istomin, who is ranked 33 places below him.
With the win, the U.S. takes an unassailable 3-1 lead over Uzbekistan and completes a comeback from 1-0 down on Friday.
The fifth rubber later Sunday pits world No. 47 Steve Johnson against 158th-ranked Uzbek Farrukh Dustov.