Jack Sock overcame a two-set deficit to beat Marin Cilic 4-6 3-6 6-3 6-4 6-4 and give the United States a 1-0 lead over Croatia on Friday in the best-of-five Davis Cup quarter-final.
The 23-year-old Sock, playing in his first career home Davis Cup tie, won the fifth set after breaking Cilic to take a 5-4 lead on the Tualatin Hills hard court.
Sock won the last four points of the final game, claiming the three-hour, 13-minute match when Cilic hit his final shot into the net.
In the second singles match Friday, the US’s John Isner faced Borna Coric.
The Davis Cup tie continues through the weekend, with a doubles match Saturday, and two reverse singles matches Sunday.
Cilic, the 2014 US Open champion and current world No.12, was tough early on, breaking Sock’s serve late in the first two sets to take a 2-0 lead.
The big-serving Sock bounced back, using an early service break to win the third set.
Sock, No. 26 in the world, then pulled even, winning the fourth set by claiming the final two games.
The US last hosted a Davis Cup match in 2014, when it lost in the first round to Britain in San Diego.
This is the fourth time Portland has hosted a Davis Cup tie.
The US is trying to break a nine-year Davis Cup title drought.
The US won in 2007 when it beat Russia 4-1 in Portland. Croatia claimed its only Davis Cup title in 2005.
The US has won a Davis Cup-high 32 titles, but only one since 1995.