South Korea blew a chance to qualify for the FIFA World Cup after getting held to an undermanned Iran at home on Thursday.

South Korea failed to get past 10-man Iran in their World Cup qualifier at Seoul World Cup Stadium, and their hopes of securing their ninth consecutive trip to football's showpiece event remain up in the air with one match remaining in the final Asian qualifying round.

South Korea are still in second place in Group A, thanks to Uzbekistan's 1-0 loss to China also on Thursday.

South Korea now have 14 points, two clear of Syria and Uzbekistan before their crucial showdown against Uzbekistan in Tashkent next Tuesday.

Syria have emerged as an unexpected threat to South Korea's World Cup hopes after beating Qatar 3-1 Thursday. They hold a goal difference tiebreak edge over Uzbekistan. If Syria upset Iran in their final qualifier and South Korea lose to Uzbekistan, then Syria will get through.

Syria held Iran to a 0-0 draw last November.

In Asia, only the top two teams from Groups A and B will advance directly to the 2018 FIFA World Cup in Russia. Two third-place nations will drop to the playoffs for a final chance to qualify.

Iran had already booked their spot before Thursday's match, and improved to 21 points in Seoul.

South Korea haven't beaten Iran since January 2011. Their four previous meetings had all ended in 1-0 victories for Iran.

South Korea had the match's first opportunity in the 17th, when Son Heung-min's free kick from just outside the box deflected off an Iranian player and out of play.

Jang Hyun-soo nearly headed home South Korea's first goal in the 19th minute following a long-distance free kick, and his missed attempt turned out to be South Korea's last scoring opportunity in the tightly-contested first half.

Iran had one shot on net in the opening half, as forward Reza Ghoochannejhad, with three South Korean defenders on him, still fired a hard shot right at goalkeeper Kim Seung-gyu in the 37th minute.

The pendulum appeared to swing in South Korea's favor in the 52nd when Iran midfielder Saeid Ezatolahi was sent off for a hard foul on Kim Min-jae. Following an aerial battle for a loose ball, Ezatolahi, who was hit in the face, stomped on Kim's head while the South Korean was on the ground.

South Korea failed to exploit their man advantage or put much pressure on Iran.

South Korea won another free kick close to the box in the 77th, but midfielder Kwon Chang-hoon airmailed the ensuing opportunity.

The hosts' efforts down the stretch all proved futile, as Iran remained undefeated in the current qualifying round.

South Korea head coach Shin Tae-yong rued the team's inability to solve Iran's defense despite the man advantage.

"It's a pity that we couldn't score, but I want to thank our players who gave their best," Shin said. "I knew we were going to have a difficult match against Iran that have shrewd players with good physical abilities."

South Korea played Iran twice in the final qualifying round and failed to put a shot in the net in both matches. (Yonhap)