It had been 5,283 days since China last won a knockout game at an international tournament.

The wait ended in the United Arab Emirates on Sunday as Marcello Lippi's squad eked out a 2-1 come-from-behind victory over Thailand to reach the quarterfinals of the Asian Cup.

The nervy manner of the triumph, though, does not bode well for Thursday's last-eight meeting with a formidable Iran side in Abu Dhabi.

Spearheaded by Rubin Kazan forward Sardar Azmoun-dubbed the 'Iranian Messi'-and managed by Portuguese former Real Madrid coach Carlos Queiroz, Iran brushed aside Oman 2-0 in its last-16 clash to remain unbeaten at the tournament. Its only hiccup thus far was a scoreless group-stage draw with Iraq.

In contrast, China's road to the last eight has been considerably bumpier, with 2-1 victories over Kyrgyzstan and the Thais, either side of a 3-0 stroll against the Philippines, tempered by a 2-0 loss to South Korea.

The last time China beat Iran was in a 2009 friendly.

If China's aging squad is to have any hope of causing an upset on Thursday, it will need to produce a better start than it managed against Thailand, which capitalized on panicky defending to take a 31st-minute lead through Supachai Jaided.

"I'm satisfied with the victory, but it doesn't mean it was an easy win as Thailand was a tough team," said Lippi, who is set to leave the job when his contract expires at the end of the tournament.

"We made many errors in the first half, but we came to life in the second 45. We created many scoring chances and seized the opportunities."

Xiao Zhi came off the bench to finally break the Thais' resistance in the 67th minute when he followed up his own saved header to poke home.

Four minutes later, Gao Lin was fouled in the area before dusting himself down to convert the resulting penalty and seal the win.

"We had many mistakes in the first half of the match, so I was so happy to score the goal," said Guangzhou R&F attacker Xiao, who at 33 was remarkably making his Asian Cup debut 14 years after turning pro.

"We did not give up in the second half. We were a little anxious, but we believed that we could score. Although we scored the goals a little bit late, the main thing is we finally won. We've achieved our goal."

Sunday's first-half horror show was similar to the team's early struggles against Kyrgyzstan, which also benefited from China's statuesque defending and glaring lack of composure in possession.

Those shortcomings will be punished more severely if repeated against Iran, the outright favorite with some bookmakers to lift the trophy.

"We were too nervous at the start of the game, and some players struggled to make the right moves," said China's 38-year-old captain, Zheng Zhi. "However, we made a lot of adjustments after the break and the communication was a lot better.

"We created many chances to score. In knockout games, if you miss chances you'll definitely lose. Luckily, we managed to hold onto the lead until the final whistle."

China's campaign has been made that much tougher by fitness and injury problems.

Sunday was scoring hero Xiao's first match in the UAE as he was recovering from a pulled muscle.

Star striker Wu Lei has been hampered by a shoulder problem, with last season's Chinese Super League top scorer looking out of sorts against the Thais after getting off the mark with an impressive two-goal haul against the Kyrgyz.

With an average age of 30, China is the oldest squad in the tournament. Endurance is not one of the team's strengths-a factor all too obvious against the spritely Thai team in the dying minutes of Sunday's game.

Lippi, though, said the veterans have been picked on merit and he is banking on their experience to make up for their lack of mobility.

"There are few young players who were capable of the job," said the Italian, defending his selection.

"After the Asian Cup, it will be a problem if no strong young players emerge. The rich experience veterans possess is their advantage."