Korea Republic got back to winning ways in the third round of Asia's FIFA World Cup qualifying, solidifying its grip on second place in Group A with an unconvincing 1-0 win over Syria.

Hong Jeong-ho's half-volley put Korea ahead early on, but any hopes of it responding to a 1-0 defeat to China in its previous qualifier with a resounding victory proved false.

Syria, itself in the running for a play-off spot, did not lack ambition but the quality in its final ball was missing for much of an entertaining encounter in Seoul.

Yet the visitors created plenty of opportunities, substitute Firas Al Khatib coming closest when he rattled the crossbar in second-half stoppage-time.

Defeat means Syria remains a point shy of Uzbekistan, which occupies the play-off spot and host struggling Qatar later on Wednesday (AEDT).

Korea, meanwhile, cemented its grip on the second automatic berth to qualify for the 2018 finals in Russia ahead of a meeting with Qatar in June.

The breakthrough came inside four minutes for Korea, Hong lashing into the bottom-right corner after Syria had failed to deal with Son Heung-min's corner.

Korea had an appeal for a penalty turned down despite Nam Tae-hee's effort from outside the box appearing to strike a Syria player on the hand.

Syria saw a penalty shout of its own ignored when Omar Kharbin had an effort blocked but it should have levelled in the 30th minute.

Korea was unable to cope with a free-kick from the left but Syria was unfortunate to see the ball fall to full-back Alaa Al Shbli, who fired narrowly over from point-blank range.

Syria continued to grow in confidence in the second half but the game was almost put out of their reach in the 56th minute, Nam going agonisingly close to turning another fine delivery from Son into the bottom-left corner.

Ibrahim Almeh then had to be alert to deny Hwang Hee-chan before Nam stung the palms of the Syria goalkeeper.

But the hosts were grateful to Kwoun Sun-tae for preserving their slender lead as he kept out Al Khatib's fierce close-range effort after the substitute had gone through on goal.

Almeh raced off his line to prevent Son from latching on to a throughball and only the woodwork prevented Al Khatib from punishing Korea's profligacy and earning a point for a spirited Syria side.