LOS ANGELES - Jack Sock rallied to beat Marin Cilic 4-6, 3-6, 6-3, 6-4, 6-4 on Friday to give the United States a 1-0 lead over Croatia in their Davis Cup World Group quarter-final tie.
US player Jack Sock, pictured in Wimbledon, southwest London, on July 2, 2016, is ranked 26th in the world
Sock, ranked 26th in the world, fired 17 aces. He surrendered an early break in the fifth set, but broke back in the fifth game.
Cilic, the 2014 US Open champion ranked 12th in the world, fended off three break points in the seventh game, but Sock gained the last break he needed in the ninth game when Cilic sent a high backhand volley wide.
Sock surived two break points in the next game to seal the match after three hours and 13 minutes.
John Isner, ranked 16th in the world was trying to consolidate the hosts' lead in the best-of-five match tie when he met rising Croatian Borna Coric, ranked 54th, in the second singles later Friday at Tualatin Hills Tennis Club in Portland, Oregon.
While the United States are the most successful Davis Cup nation ever, with 32 titles, they were ousted in the first round the past two years by Britain.
The winners of the best-of-five match tie will take on either the Czech Republic or France in the semi-finals. The Czechs and French were tied 1-1 after the opening day of their tie in Prague.