Sardar Azmoun scored the only goal of the game as Iran took a huge step towards Russia 2018 with a 1-0 victory over South Korea in Tuesday's World Cup qualifier in Tehran.
The Rostov striker clinically side-footed home in the first half as Iran benefited from a lively start in front of their home supporters.
But the manner of the win will matter little to Carlos Queiroz's team, who now have 10 points from four Group A matches.
Uli Stielike's South Korea side remain on seven points and will look to bounce back swiftly against Uzbekistan next month.
Iran were lively from the outset and Alireza Jahanbakhsh swept the ball home from eight yards, only for Morteza Pouraliganji to be ruled offside in the build-up.
Jahanbakhsh then wasted a gilt-edge chance when he volleyed Ehsan Hajsafi's whipped free-kick into the ground and over from just outside the six-yard box.
The pressure finally told in the 25th minute, though. Ramin Rezaeian found space down the right and played a low pass into the area where Azmoun brilliantly guided his first-time shot into the bottom left-hand corner.
South Korea struggled to threaten in their attempt to respond to that setback, and the hosts' upped the ante slightly in the early stages of second period as they sought to double the lead, Jahanbakhsh firing over from the edge of the area.
Kim Seung-gyu did his part to keep South Korea in the contest with a fine low stop from Jahanbakhsh's edge-of-the-box drive.
