Japan went ahead through a Yasuhito Endo free-kick on 21 minutes, only for Narongchai Vachiraban to equalise with a sizzling shot just a minute later.
The home team had to wait for more than half-an-hour before Yoshito Okubo pounced on a deflected clearance to restore their lead on 54 minutes.
Thailand's hopes of a recovery looked bleak when Narongchai received his second yellow card for pulling down Yuji Nakazawa.
And Nakazawa leaped to head home a free-kick on 66 minutes to stretch Japan's advantage to 3-1, before substitute forward Seiichiro Maki completed the scoring in injury time.
■ SOUTH KOREA V TKM
AP, SEOUL
Park Ji-sung's first goal for his country since the 2006 World Cup and two from Seol Ki-hyeon helped South Korea stroll to a comfortable 4-0 win over Turkmenistan in their opening 2010 World Cup qualifier yesterday.
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