Rebounding from their shock early exit from 2010 World Cup qualifying, China moved top of Group D after a Gao Lin hat-trick, and Bahrain made the Group A headway with a 3-1 win away to Hong Kong.
UAE moved top of Group C after thrashing a hapless and breathless Malaysia 5-0 in Kuala Lumpur.
Two goals apiece from Mohamed Omar and Ismail Mater and a late strike from Ahmed Khalil embarrassed the hosts, whose depleted squad had only three members deemed fit enough to play.
"I was prepared for only a one goal victory. I really didn't expect such a big win," UAE coach Dominique Bathenay told reporters. "They did a good job and were fully committed to winning this match."
Gao put China ahead after only one minute in Zhejiang, only for Nguyen Vu Phong to level for the Southeast Asian champions nine minutes later.
China then went into overdrive, with Gao adding a second on 21 minutes followed by goals from Du Wei (29) Jiang Ning (37), and Hao Junmin (47). Gao netted his third seven minutes from time to give China the group lead on goal difference.
In Hong Kong, Ismaeel Abdullatif and Abdulla Fatadi put Bahrain two up inside 37 minutes. Salman Isa scored a third close to the end before Isa Cheng Siu pulled one back in stoppage time.
Bahrain coach Milan Macala said the win was "very important" but criticised his team for being complacent while ahead.
"We looked like we were celebrating and Hong Kong were strong and aggressive," he said. "The players came out like the game was over and allowed Hong Kong to think they had a chance."
The top two teams in each group will advance to the 2011 finals, where they will meet hosts Qatar, champions Iraq, Saudi Arabia, South Korea and India.
