South Korea's offense went silent Thursday against Saudi Arabia in their final test ahead of next week's Olympic football qualifying tournament, a concerning development for a squad that has often had trouble finding the back of the net.

South Korea's under-23 squad only mustered a scoreless draw against Saudi Arabia in Dubai on Thursday, two days after defeating the United Arab Emirates 2-0, also in Dubai, with a much more energetic attack in the second half.

In the opening 45 minutes against Saudi Arabia, there was nothing to write home about for South Korea. 

Lee Seul-chan hit the crossbar near the half-hour mark, and that was as close to scoring as South Korea got in this match.

For the second straight match, head coach Shin Tae-yong elected to bench some key offensive players at the start, hoping his regulars would come off the bench to provide some spark in the second half. 

Forward Hwang Hee-chan, one of the goal scorers against the UAE, and midfielder Kwon Chang-hoon, the team's most creative playmaker, entered the match to open the second half, and they quickly changed the pace of the match.

Hwang, the youngest South Korean at 19, was the lone bright spot on offense. 

The Salzburg striker played with controlled abandon deep in the Saudi zone, his speed and aggression causing havoc among flustered defenders. 

Hwang event set up a breakaway opportunity for forward Kim Hyun, who wasted it by rolling one weakly out of play.

Despite yeoman's work put in by Hwang, South Korea failed to sustain their early momentum in the second half, and were actually lucky to walk away with the draw. 

Goalkeeper Kim Dong-jun made an outstanding save to deny Saleh Al Jamaan from point-blank range in the 83rd.

Unlike the previous match, Shin, the head coach, played his four defenders the full 90 minutes.

They visibly tired in the late moments, and fell a step or two behind Saudi attackers in their own zone.

South Korea will only have a few days to address their issues.

They will travel to Qatar Friday for the AFC U-23 Championship, which kicks off Tuesday. 

In Group C, South Korea will play Uzbekistan next Wednesday, followed by Yemen on Jan. 16 and Iraq on Jan. 19.

The top two nations from each of the four groups will reach the quarterfinals. 

Only the top three nations overall will qualify for the Rio de Janeiro Summer Games.

South Korea won bronze at the 2012 Olympics in London, the country's first Olympic medal in football. They have competed in every Olympics since 1988. (Yonhap)