And it was Al Haydos's 66th-minute stunner that proved the difference in front of more than 40,000 fans, the captain volleying home from the edge of the box direct from a corner.
Qatar, already qualified for the last 16 after wins over Lebanon and Tajikistan, made nine changes to the team that faced China at the Khalifa International Stadium in Al Rayyan.
China fluffed the best chance of the first half five minutes later when Wei shot against goalkeeper Saad Al Sheeb's legs from point-blank range.ge of the box direct from a corner.
"All 26 players played in our three matches and we gave a spectacular performance," said the 33-year-old forward.
"These three points are very important for our morale. We have finished with maximum points and now we will concentrate on the last 16."
It has been a promising start to the title defence for the 2019 champions, who are yet to concede in the tournament and will face one of the four best third-placed sides in the last 16.
China's hopes of being one of those teams took a major hit with the defeat to Qatar, combined with Tajikistan's 2-1 win over Lebanon in Monday's other Group A match, which sent the newcomers through to the knockout stages.
China will need a mathematical miracle to join them and manager Aleksandar Jankovic said they only had themselves to blame.
"In the three games we played, a lot of chances we missed every game," said the Serbian. "If you don't score, you cannot expect a big result. We are disappointed of course because our destiny doesn't depend on us anymore."
China began the tournament with two dour goalless draws against Tajikistan and Lebanon, and they again looked toothless in front of goal against Qatar.
Jankovic said he stood "firmly behind" the players and had "no regrets because we gave everything". He also said he was unafraid of paying the price with his job for another Chinese footballing failure.
"There are two types of coaches in general – those who have been fired and those who will be fired," he said. "When you accept to do this job, you accept both. The one who thinks about the moment when he will stop working is the one who is afraid of everything. The guy who is afraid of everything cannot be a coach."
While Qatar coach Tintin Marquez made sweeping changes to his starting lineup, including resting forward Akram Afif, the competition's joint top-scorer on three goals, Jankovic dropped out-of-sorts forward Wu Lei and brought in Wei Shihao, who went close with a dangerous shot early in the game.
China fluffed the best chance of the first half five minutes later when Wei shot against goalkeeper Saad Al-Sheeb's legs from point-blank range.
Striker Zhang Yuning also had a good opportunity in first-half injury time but could not get on the end of Wei's low ball into the box.
"At this moment we are not lucky to score but this is something very important for the future," said Jankovic. "I'm sure that the moment will come when all these balls will go in."
