Qatar produced a huge defensive effort to scrape a goalless draw against Iran in their World Cup qualifier in Tehran on Tuesday.
Roared on by 100,000 supporters at the Azadi Stadium, Iran dominated possession but struggled to break down a determined Qatari backline, who had shown several defensive lapses in a 4-1 defeat at home to South Korea on Friday.
Iran captain Javad Nekounam had the home side's best chance when he hooked a right foot shot against the crossbar in the 30th minute.
Qatar, aiming to reach their first World Cup before they host the tournament in 2022, seemed content to waste time and play for the draw, with their goalkeeper Qasem Burhan forcing numerous stoppages in play claiming injury.
The negative tactics frustrated the home side, who were guilty of playing too direct and tossing long balls into the box that Burhan dealt with easily.
The result left the two sides with four points in Group A, although Qatar have played three matches to Iran's two.
South Korea lead the standings on six points after they outclassed Lebanon 3-0 earlier on Tuesday.
Iraq were guilty of wasting several good chances on Tuesday when they were held to a disappointing 1-1 home draw by Oman in a World Cup qualifier in Doha.
The 2007 Asian champions, forced to play their home matches in Qatar because of security fears, were the better side but frustrations boiled over in their Group B clash after they failed to make the most of their dominance.
With 10 minutes left, Iraqi captain Younis Mahmoud beat two players but, falling off balance, fired a left-foot shot well wide as left--winger Karrar Jassim attempted to strike the ball.
The two were left arguing with their legs tangled and Oman comfortably played out the final minutes to collect their second draw in three fourth-round matches.
The visitors had taken the lead against the run of play when Mohammed Al Balushi leapt highest to flick home a free-kick from deep in the eighth minute.
Iraq, trying to qualify for their first World Cup finals since 1986, regrouped and levelled from the penalty spot when Amad Ali, standing in the defensive wall, was adjudged to have blocked Younis's free-kick with his hand.
The Iraqi captain stepped up to send a cheeky chip straight down the middle eight minutes before half-time.
Oman had a good spell at the start of the second half. Ahmed Mubarak came close to snatching a second goal but his free-kick from the edge of the penalty area curled just wide.
It was a second draw for Iraq in Group B and they remain second in the five-team pool behind Japan, who were held to a 1-1 draw by Australia who collected their first point.
Iraq next play away to Asian champions Japan in September.
South Korea 3 Lebanon 0
Iran 0 Qatar 0
Australia 1 Japan 1
Iraq 1 Oman 1