Japan's World Cup qualifying preparations were dealt a blow Wednesday when playmaker Shinji Kagawa suffered a shoulder injury in a 1-1 home draw with Syria.

The Borussia Dortmund midfielder was stretchered off just nine minutes into the Tokyo friendly clutching his left shoulder after an awkward fall, and could be in doubt for next week's Asian qualifier against Iraq.

Syria took a shock lead early in the second half when forward Mardik Mardikian powered home a header after clever work on the right by Amro Jenyat.

Japan equalised after 59 minutes, Inter Milan left-back Yuto Nagatomo squaring for Yasuyuki Konno to apply a simple finish from point-blank range.

Keisuke Honda and Takashi Inui went close as Japan pushed for a winner. But the Blue Samurai produced little that will strike fear into Iraq when the teams square off in neutral Tehran on Tuesday.

Japan currently top Group B in the final round of Asian 2018 World Cup qualifiers with 16 points from seven games, ahead of Saudi Arabia on goal difference.

Australia, the reigning Asian champions, are three points behind the leaders with three matches left to play.

The top two teams from each of the two groups qualify automatically for next year's World Cup in Russia.