Qatar took the lead after 27 minutes of their second Group A game when Ahmed scored the goal of the tournament at the Khalifa Stadium.
Collecting a lofted forward pass on his thigh, he smashed an unstoppable, swerving volley into the roof of goalkeeper Zeng Cheng's net from the edge of the penalty area to send the crowd into raptures.
Ahmed made it 2-0 on the stroke of half-time when China's imposing captain Du Wei allowed him too much time to turn, shoot and, to his horror, score with a low hooked shot from almost the same place as his first goal.
Qatar's French coach Bruno Metsu was a relieved man after his team redeemed themselves after the abject performance in the opening match of the tournament when they lost 2-0 to Uzbekistan.
"We wanted to show the real face of our team tonight and that's what the players did," Metsu told reporters. "I am very proud of their performance and we will try and do the same against Kuwait to qualify for the next stage.
"I think we sent a good message to the fans and I think they were very satisfied tonight."
"I said to him at half-time, even if we had (Italian goalkeeper) Gianluigi Buffon in goal he couldn't have stopped the two goals. I am happy with his performance," said the coach.
The mood could hardly have been more different than the almost funereal atmosphere during Friday's defeat by Uzbekistan when the crowd left in droves long before the end.
