PORTLAND, Ore. -- The odds stacked against his underdog side, Croatian captain Zeljko Krajan was brimming with confidence Sunday morning before the reverse singles match in the Davis Cup quarterfinal tie against United States.
"Today, I knew they were going to bring the quality," Krajan said.
The U.S. lost for the fourth time in 161 tries when leading 2-0 lead in a Davis Cup tie.
"It's really unbelievable," Krajan said. "I would say shocked from this win. Looking back on Friday and being 2-love down and then playing against the Bryans yesterday, it didn't look very positive for us."
Croatia will host France -- a 3-1 winner at the Czech Republic -- in the World Group semifinals Sept. 16-18. Croatia reached the semifinals for the first time since 2009. It won its only Davis Cup title in 2005.
In the other semifinal, defending champion Britain will host Argentina.
Cilic set the tone for the comeback against Isner, a decision that was closer than the score indicated. Cilic won a marathon tiebreaker in the opening set, then broke Isner's serve once in the next two sets to pull out the win.
The opening set was riveting. Isner was hot, allowing Cilic to win only one point during his first 25 serves. But the American was unable to break Cilic, forcing a tiebreaker. Cilic won a couple points off Isner's serve late in the tiebreaker to pull out an 11-9 win, setting off a torrent of emotion along the Croatia sideline.
"That was definitely a tough task, but I stayed in there mentally," Cilic said. "I was very, very focused."
Isner was clearly disappointed he didn't get the jump on Cilic.
"The first set was critical. Felt like I definitely was the better player in the first set. Didn't get paid off, but that's on me. He came up with the goods when he needed it. That gave him a lot of confidence, I think," Isner said.
U.S. captain Jim Courier disagreed that momentum swayed in Croatia's favor after Cilic pulled out the first set.
"That's not the way we look at it. First sets can be critical ... these matches are won on small margins. There are a couple points that go our way, and we're sitting here with a smile on our face instead of a little disappointment," Courier said.
Unlike Friday's first singles match, when Cilic lost after leading Sock by two sets, the world's No. 12-ranked player finished off Isner by breaking him in the ninth game to pull out a 6-4 win.
Cilic is 6-0 against Isner.
The 19-year-old Coric is becoming a reliable closer for Croatia. It was the second time this year Coric won a fifth and deciding match to win a Davis Cup tie.
"I have to be honest. I like that kind of situation," Coric said. "I like it more than playing on Court 27 somewhere, somewhere far away from the crowd. I just like the big stage more, when it's more important."
After splitting the first two sets against Sock, Coric won the final two sets by breaking the American's serves four times. Coric's performance was decidedly stronger than his three-set loss to Isner on Friday.
"I was much more relaxed," Coric said. "I was hitting the ball, going for the points. I just wasn't waiting for him to miss, because I knew I cannot play like that because he's going to kill me with the forehand."
Sock, who beat Cilic in a five-setter Friday, was upbeat despite dropping the finale.
"Obviously, I had chances and opportunities that I didn't convert. That's tennis. Some days it's firing and some days they're missing a little bit. He played a great match," Sock said.
Croatia is 4-0 in Davis Cup ties against the United States.