Qualifier Ricardas Berankis reached the first final of his ATP career with a 7-5, 6-1 defeat of Australian sixth seed Marinko Matosevic at the Los Angeles Open.
Berankis, a former world junior champion from Lithuania, will play either two-time champion and second seed Sam Querrey or Rajeev Ram, both of the US.
Berankis waited for his moment against Matosevic, breaking the seed in the 11th game of the opening set from a forehand error.
A game later, after 45 minutes of battle, the 22-year-old youngster had the set in his pocket. That momentum opened the floodgates as the first qualifier to reach a Los Angeles final since 2009 tightened his grip with a 5-1 lead.
Berankis clinched his record-setting victory a game later on the second of three match points, ending with 18 winners and four breaks of his Australian opponent.
Berankis did not lose a set all week in his main draw matches and got through qualifying with only one set dropped a week ago.
"I saw Marinko play this week and felt I could get on to his second serve and take advantage. I tried to do that from the first point and it worked," he said.
The winner ran to the stands to embrace his coach in the moment of victory at the UCLA campus facility. The pair share a father-son bond after the players' best friend - his coach's son - was killed in a traffic accident seven years ago.
"It was the most important thing for me that my coach was able to fly in for this match," said Berankis.
Berankis, who kept an even keel throughout one of the biggest matches of his life, has never played Querrey but practised a month ago with Ram, an old-school serve-and-volleyer.
"I realised that if I stay calm I have a better chance to win, that's the main thing, stay focused and play my game as best as I can."
Berankis said that his accomplishment will no doubt make a bit news at home even amid the London Olympic excitement.
"This is an unbelievable thing for us, we are a small country and have some tough conditions. I'm happy about this."
The best previous results for Berankis were a pair of quarter-finals in San Jose in 2010-11.
Berankis hopes to become the second qualifier to win an ATP title this year after Finn Jarkko Nieminen accomplished the feat in Sydney in January.