The latest instalment in one of football's great rivalries failed to live up to their classic 2015 quarter-final, won by Iraq on penalties, as a raw and uncompromising first half gave way to a more measured second period.

It meant that Iran, Carlos Queiroz's three-time winners, finished top of Group D on goal difference after their 5-0 thrashing of Yemen and 2-0 win over Vietnam.

Iran welcomed back Brighton's Alireza Jahanbakhsh, last season's Eredivisie top-scorer, from injury as they set about going unbeaten for a 20th straight game at the group stage.

And in a physical first half in front of a deafening crowd, Iran, Asia's top-ranked side, were largely on top but couldn't make their advantage count.

As the challenges flew in, Jahanbakhsh and Iraq's Safaa Hadi both wiped away blood, and Iranian midfielder Saman Ghoddos was lucky not to see red for a stamp.

Iran's Sardar Azmoun came close with a header, Ghoddos saw a powerful drive deflected away and Jahanbakhsh fizzed one over on the rebound. Iran also strongly claimed a penalty when Hadi handled accidentally.

At the other end, Ahmed Yasin's low shot was just off target and 18-year-old forward Mohanad Ali, scorer of a brilliant solo goal against Yemen, glanced a header wide.

Jahanbakhsh withdrew just after the hour mark and Iraq's Ali followed shortly afterwards, following a final attempt which the teenager drove straight down the throat of goalkeeper Alireza Beiranvand.

It looked like both sides were happy to settle for a draw before Iraq's Humam Tariq swung a cross to substitute forward Alaa Abbas, whose header was acrobatically palmed away by Beiranvand.

However, clear-cut chances were scant in the second half as the former war-time foes saved their energies for the bigger challenges to come in the knockout phase.