ABU DHABI - Back-from-retirement Sardar Azmoun fired Iran into the Asian Cup knockout phase on Saturday as Carlos Queiroz's side reached the last 16 along with arch-rivals Iraq, with Saudi Arabia on the brink of joining them.
Azmoun, 24, quit the national team after fans rounded on him following Iran's exit at last year's World Cup, but he was the toast of Tehran once again with both goals in a 2-0 win over Vietnam.
Saudi Arabia, who like Iran are three-time former winners of the Asian showpiece, beat Lebanon 2-0, while teenager Mohanad Ali inspired 2007 champions Iraq to a 3-0 win over Yemen.
Iran and Iraq, with four titles between them, joined already qualified South Korea, China and Jordan as the round of 16 began to take shape.
Queiroz singled out Azmoun after the Rubin Kazan forward's double made him the tournament's top scorer with three goals, and gave Iran a record ninth successive first-round victory.
"He's a finisher," said the Portuguese, now in his eighth year as Iran coach.
"We have high hopes for him for this competition. But the way the team is contributing around him, and our movement in the last third, are very interesting."
Iran, looking to end a 43-year title drought since last winning Asian football's most coveted prize, could have scored four or five but for some poor finishing in Abu Dhabi.
"It's a pity our performance didn't produce a couple more goals," Iran coach Queiroz told reporters.
"But winning is the best medicine in football. To win two games and score seven goals -- I have to praise my players because I am very demanding."
Saman Ghoddos and Mehdi Taremi went close for Asia's top-ranked team before Azmoun rose to head home a Ghoddos cross after 38 minutes.
Azmoun lashed in his third of the tournament from the edge of the box 20 minutes from time to make it seven unanswered goals for Iran, who crushed Yemen 5-0 in their opening Group D game.
In Sharjah, 18-year-old Ali scored a wonderful solo goal to put Iraq 1-0 up after 11 minutes, although questions must be raised of the Yemeni defence.
Pouncing on a loose back pass, Ali held off three defenders before rifling his shot past Yemen goalkeeper Jalal Hassan for his second of the tournament.
Bashar Resan doubled Iraq's lead midway through the first half when his deflected shot drifted in off the upright with Hassan slow to get across.
Ali hit the post in one of the rare highlights of the second half before Alaa Abbas grabbed Iraq's third in injury time, finishing sharply after Ahmed Yaseen's header into his path.
Iran and Iraq will meet in Dubai on Wednesday to decide who tops Group D in a repeat of their combustible quarter-final of 2015, which Iraq won on penalties.
Saudi Arabia also maintained their perfect record as they beat Lebanon 2-0, winning their opening two games for the first time since 1996 -- when they last won the title.
Fahad Al-Muwallad smashed a loose ball into the roof of the net with just 12 minutes gone, and on 67 minutes Hussain Al-Moqahwi finished at the far post from Hatan Bahbri's teasing cross.
The Saudis, who top Group E with six points, will be confirmed in the last 16 if North Korea fail to beat Qatar on Sunday.