By ESPNSTAR.com staff
Reigning Malaysia Super League and FA Cup champions Kelantan suffered the worst fate of the lot, falling to a 5-1 defeat at Iraqi side Arbil.
Halgurd Mulla Mohammed opened the scoring for the hosts in the 38th minute, but Red Warriors captain Badri Radzi equalised from the spot three minutes later to ensure both sides went in at the break level.
However, Nizar Mahrous' charges came out after the break with all guns blazing and edged ahead again thanks to a Amjad Radhi penalty five minutes into the second half, before goals from Luay Salah and Salih Sadir (2) handed Arbil a comprehensive victory.
Thailand Premier League outfit Chonburi failed to hold on to an early lead as they succumbed to a 2-1 home defeat at the hands of Syrian side Al Shorta.
Brazilian forward Thiago Cunha fired the Sharks ahead after just three minutes but Oday Jafal levelled the scores in the 39th minute, before Geilson scored what proved to be the winner five minutes later.
Indonesian giants Arema were also beaten at home as they were defeated 2-0 by Al Ettifaq courtesy of second-half strikes from Yahya Al-Shehri and Zamil Al-Sulim.
Finally, Al Kuwait and Al Wehdat played out a 0-0 draw at the Al Kuwait Sports Club Stadium.
Tuesday's AFC Cup Quarter-final First-leg Results
Arema 0-2 Al Ettifaq
Chonburi 1-2 Al Shorta
Arbil 5-1 Kelantan
Al Kuwait 0-0 Al Wehdat