The US men's team trailed a new lineup, as a total of seven players made their debut in the match and the average age of the starting 11 was just 23 years old.
Llanez's winning goal came in the 50th minute but aside from the goal, Llanez had a perfect debut. He started the match on the left wing and was constantly getting up and down the flanks and into dangerous positions on Saturday, reports Xinhua news agency.
"Llanez plays with confidence and I think you saw even in the beginning of the game, you didn't see nerves, he's going one on one at guys, he's getting into good spaces, he's running all the time. Real good combination of things he did in the game," said US coach Gregg Berhalter.
"Gregg gave me the start and he believed in me and I felt like I showed them out there that I can be in more camps with him," Llanez said after the match.
Llanez joined the Galaxy Academy in 2015 and used to play for Galaxy II, a reserve team of the MLS giants, but he left last year to sign a professional contract with German club Wolfsburg.
"My main focus is Europe," he said. "I feel like I have a chance to become something big. I'm just focusing on my soccer."
The US team's next match will be another friendly against the Netherlands on March 26.
( With inputs from IANS )