South Korea triumphed 2-0 in extra time in Melbourne thanks to a brace by Son Heung-min, but the game could have gone either way during regulation with both sides wasting a number of decent scoring opportunities.
Uzbekistan arguably had the two best chances of the opening 20 minutes with Lutfulla Turaev just failing to make contact with a diving header, directly in front of goal, before captain Odil Ahmedov volleyed over the bar from six yards.
Turaev also failed to convert a header in the second half when left unmarked at the back post and, although Uzbekistan were overrun in extra time, Qosimov insisted his team had done enough to progress to the final four.
"We were unlucky today. So because of our lack of luck we are very disappointed," the 44-year-old coach said.
"As you saw, we could score many, many goals but luck was not on our side so that is why we didn't win."
Son struck in the 104th minute after Uzbekistan failed to clear the ball from their defensive third, heading into the net from close range.
The Bayer Leverkusen winger added another goal with two minutes remaining in extra time, smashing the ball into the roof of the net from the edge of the box.
But despite Son's heroics, South Korea central defender Kwak Tae-hwi was named man of the match, as he helped his team to their fourth consecutive clean sheet of the tournament.
For Qosimov, that just served to prove his team had shown more in the final third than their opponents.
"If we scored today I don't think he [Kwak] would be the player of the match, I think our forwards would be the best players," he said.
