A Milos Ninkovic goal gave Sydney FC a crucial 1-0 win over South Korea's Pohang Steelers to maintain their lead in Group H in the AFC Champions League on Tuesday.

The Serbian midfielder scored the winner in the 51st minute for Sydney's third straight win and completed a double over the three-time ACL champions in the group.

Last month Sydney FC upset Pohang 1-0 in South Korea and their follow-up home win has put the Steelers in big trouble to advance to the knockout stages of the tournament.

After a drab opening half, Ninkovic brought the game to life when he scored at the second attempt after two Pohang defenders failed to clear the ball.

Defender Matt Jurman almost doubled the advantage when his piledriver was brilliantly saved by Kim Jin-Young in the 73rd minute.

"It was a very difficult game for us after our loss to Adelaide last weekend but it was a big victory for us and we are in a good position to advance now," Ninkovic said.

So effective was the Sydney defence that their goalkeeper Vedran Janjetovic did not make a save during the match.

Sydney FC continue to enjoy a winning run in the ACL despite a miserable A-League campaign where they are out of the running to the make the top-six playoffs this season.

The Sydneysiders next face Japanese giants Urawa Red Diamonds at home on April 20 in a match where a draw could be enough to get them through to the last 16.