Iran say they will be "more united" in the Asian Cup quarterfinals after surviving extra time with 10 men before defeating Syria on penalties on Wednesday.

After the match ended 1-1 after 120 minutes, Iran held their nerve to win 5-3 in the shootout and face pre-tournament favourites Japan on Saturday.

Iran played the last 30 minutes with 10 men after Porto striker Mehdi Taremi was sent off for a second yellow card with the game level at the end of normal time.

Goalkeeper Alireza Beiranvand was the penalty hero, saving Syria's second spot-kick from Fahd Youssef, and skipper Ehsan Hajsafi tucked away the winning penalty.

Midfielder Saeid Ezatolahi said he saw being dragged through extra time and penalties as "a positive".

"It is going to make us more united for Japan," he added.

Iran coach Amir Ghalenoei said he was "not happy with two or three" of his players, without saying who.

"We could have scored five goals up until the 70th minute," he said.

He was more pleased with how they dealt with being a man down.

"We were very compact and disciplined in extra time, we can be happy until tomorrow, and then we will think about Japan."

Along with hosts and holders Qatar, Iran came into the game as the only team left in the competition with a 100 percent record. They are pursuing a first Asian Cup crown since 1976.

Taremi was a central figure, winning a first-half penalty and putting it away to give Iran a deserved lead.

Syria had barely been in the game but equalised just after the hour, also from the spot, before Taremi was sent off in second-half injury time.

Syria's wily Argentine coach Hector Cuper praised his players' "sacrifice", adding: "I can't ask more of them."

The 68-year-old refused to commit his future to Syria, saying: "Next week we will sit together (with football officials) and talk and see if I will stay or if I have other options."

Taremi in the thick of it

Syria were in the knockout rounds for the first time at their seventh Asian Cup and their plan was to sit deep and hit on the break at a raucous Abdullah bin Khalifa Stadium.

The 31-year-old Taremi was in the thick of it from the off and won a penalty when defender Aiham Ousou shoved him in the back in the penalty area, sending the forward sprawling over.

Taremi silenced the jeers of the Syrian supporters by stroking in the spot-kick on 34 minutes for his third goal of the tournament.

Syria, who advanced to the last 16 as one of the best four third-placed teams, had only one shot on target in the first half and the start of the second was more Iranian dominance.

Syria twice cleared off the line in quick succession and goalkeeper Ahmad Madanieh also made two desperate saves.

Cuper threw on Colombian-born Pablo Sabbag just before the hour and it paid off immediately, Beiranvand haring out of his goal and bringing the substitute down in the box.

The referee gave no penalty but changed his mind after VAR recommended he look at the pitchside monitor, and skipper Omar Khribin held his nerve for a 64th-minute equaliser.