With a knockout berth secured, South Korea will take on Iraq with the top group spot on the line at the Olympic men's football qualifying tournament on Tuesday.

The Group C showdown at the Asian Football Confederation U-23 Championship will kick off at 7:30 p.m. Tuesday at Grand Hamad Stadium in Doha (1:30 a.m. Wednesday in Korea).

The championship is also the Asian qualifying tournament for the 2016 Rio de Janeiro Summer Games. Only the top three out of 16 nations in action will advance to the Olympics.

South Korea and Iraq have both won two straight matches to book their spots in the quarterfinals, while two others in the group, Uzbekistan and Yemen, have been eliminated.

South Korea are leading Iraq on a superior goal difference,

plus-6 to plus-3, and can clinch the group with at least a draw on Tuesday.

If South Korea win Group C, they will face Group D's runner-up in the quarterfinals at 4:30 p.m. Saturday in Doha (10:30 p.m. Saturday in Seoul). If South Korea lose to Iraq and finish second in Group C, they will then play the Group D winner in the quarters at 7:30 p.m. Saturday in Doha (1:30 a.m. Sunday in Korea).

South Korea beat Uzbekistan 2-1 to open the tournament and then pounded Yemen 5-0, with midfielder Kwon Chang-hoon scoring a hat trick.

The picture is more complicated in Group D, where three out of four nations are vying for the top two spots with one match remaining. South Korea will have to wait until Wednesday to find out who will be their quarterfinals opponent.

Jordan and the United Arab Emirates (UAE) each have four points, with Jordan ranked first on a goal difference tiebreaker.

Australia have three points and will face Jordan on Wednesday for a chance to reach the quarters. On the same day, the UAE will take on Vietnam, already eliminated from the tournament after two straight losses.

The UAE are expected to beat Vietnam and take one of the two knockout berths, while the winner of Jordan-Australia match will also move on.

South Korean head coach Shin Tae-yong has said he'd rather face the UAE than Australia in the quarterfinals. South Korea defeated the UAE 2-0 in a test match prior to the AFC competition on Jan. 4 in Dubai.

South Korea hosted Australia for back-to-back friendly matches in October, and won both games by the scores of 2-0 and 2-1.

Shin said easing up against Iraq to draw a preferred matchup in the quarters won't be an option for his side because it will likely come at the expense of the team's momentum.

"If we lose to Iraq, our players may lose some of their confidence," he said. "We have to avoid such a situation."

Iraq defeated Yemen 2-0 and then Uzbekistan 3-2. Their five goals have been scored by five different players. Midfielder Humam Tariq, who had the 82nd-minute winner against Uzbekistan, and midfielder Ali Husni, who scored against Yemen, are considered major offensive threats.

South Korea have used different formations in their first two matches. Shin used a 4-4-2 setting against Uzbekistan, with two forwards backed by a diamond-shaped midfield.

Facing the underdog Yemen, he crowded his front line with one striker and four attacking midfielders in a 4-1-4-1 formation. He employed one holding midfielder backed up by four backs on defense.

Yet over the course of the match, the coach kept tinkering, switching to 4-3-3 and to 4-4-2 formations.

The players haven't seemed fazed by these changes, as the offense has been firing on all cylinders.

"We're able to adjust and make tactical changes on the fly,"

Shin said. "The fact that we can play well without limiting ourselves to one particular formation makes us a strong side." (Yonhap)