Three-times champions Iran hit back from two goals down to salvage a controversial 2-2 draw with Oman at the Asian Cup in Chongqing, China on Saturday, defender Mohammad Nosrati snatching the equaliser deep into injury time.

Oman looked to be heading for the biggest upset of the tournament after a first-half double from striker Imad Ali in sweltering conditions in Chongqing.

But Ali Karimi pulled a goal back with a deflected shot in the 63rd minute before Nosrati struck with a looping header three minutes into stoppage time.

His equaliser was a shattering blow to Oman, who were unfortunate to lose their opening Group D game against holders Japan 1-0.

Nosrati was lucky to be on the pitch after trampling on the back of Oman goalscorer Ali moments before Karimi struck for Iran but referee Abdul Rahman of Bahrain failed to see the stamp.

That decision came back to haunt Oman when Mehdi Mahdavikia lifted a free kick into the box and Nosrati climbed to head past Oman goalkeeper Ali Al Habsi.

"Nobody believed Oman were such a good team before the tournament but we did," said Iran coach Branko Ivankovic.

"It was a very hard game and Oman deserve credit. The way we came back from two goals down was amazing."

Oman squandered several chances to secure victory, Imad Ali denied his hat-trick by a brilliant save from goalkeeper Ebrahim Mirzapour in the 58th minute.

Iran were a pale shadow of the side that beat Thailand 3-0 in their opening Group D game and looked like suffering a complete meltdown in the 40 degrees celsius heat after going 2-0 down.

Defenders Ali Badavi and Rahman Rezaei became embroiled in a violent argument in the 57th minute, slapping each other in the face after Rezaei had fouled Yousuf Shaaban on the edge of the box.

Iran improved to four points from two games following their 3-0 victory over Thailand on Tuesday. They play Japan in a crunch game on Wednesday.