Angry China fans turned on their team and applauded the visiting Syrians off the pitch after what Chinese state media called "another embarrassing defeat".
China's Serbian coach Aleksandar Jankovic blamed bad luck for the 1-0 friendly loss in Chengdu on Tuesday, which came days after they were held 1-1 by Malaysia also at home.
President Xi Jinping wants China to one day host and even win the World Cup, but they are ranked 80th in the world and confidence is rock-bottom ahead of World Cup qualifying.
Thaer Krouma scored the second-half winner for Syria, who are 94th in the FIFA rankings, in front of just over 12,000 spectators at a 60,000-capacity stadium.
The Paper, reporting from the southwestern city, said irate home fans booed afterwards and demanded refunds.
Video footage also showed the Chinese players being roundly booed and spectators chanting: "What a disgrace!"
"It was a frustrating result for us," Jankovic was quoted as saying after the defeat by state-run Xinhua news agency, which noted that Chinese fans applauded the Syrian team afterwards.
"We asked the players to react after the draw against Malaysia in terms of energy level, but unfortunately we couldn't win the match."
"It's easy for me to talk about players on the field that they were not good enough, but I don't like to do that," added Jankovic, who was appointed in February.
"Every game is different, we can still collect important information from the loss."
China face a critical few months with the start of qualifying for the 2026 World Cup, and the Asian Cup in January-February in Qatar.
Chinese football is in the grip of a major anti-corruption campaign that has seen numerous leading figures investigated or charged, including former national coach Li Tie.
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