Qatar held fancied Iran to a goalless draw to walk away with a point in their Asian qualifier at the Azadi Stadium on Tuesday.
After a 4-1 thrashing by South Korea in Doha last week, Qatar put a great deal of effort into their defence to frustrate the hosts, who have qualified for three World Cups, in front of a packed crowd at Iran's most famous football stadium.
Qatar now have four points from three matches, having beaten Lebanon in Beirut in their opening game two weeks ago. Iran, too, have four points, thanks to a win over Uzbekistan.
The Qatari defence, the subject of much ridicule after their match against South Korea, kept the Iranians at bay, hardly giving them a clear chance at goal.
A 30th minute shot by Iran captain Javed Nekounam was the best chance the hosts had, but unluckily for them the ball hit the crossbar, with goalkeeper Qassim Burhan clearly beaten.
The Qataris had a couple of half chances which they squandered.
Sebastian Soria was allowed a clear run down the right flank halfway through the first half but there was nobody to meet his cross as the ball sped across the face of the goal.
A long-range effort by Fabio Cesar was calmly collected by goalkeeper Mehdi Rehmati, who also blocked a Hassan al-Haidous header off a corner in the 34th minute