|Iran's Zob Ahan forward Ghazi Najafabadi Mohammad celebrates his crucial away goal against Suwon [AFP]
South Korean clubs Suwon Bluewings and Jeonbuk Hyundai both have work to do if they are to reach the Asian Champions League semi-finals.
Suwon were held to a 1-1 home draw in the first leg of their quarter-final against Iranian side Zob Ahan on Wednesday, while Jeonbuk Hyundai lost 4-3 at Cerezo Osaka in Japan despite taking the lead three times.
Iran's Sepahan edged the first leg against Qatari club Al Sadd in Fooladshahr 1-0, Omid Ebrahimi producing the decisive goal in the 12th minute.
Al Ittihad beat K-League champions FC Seoul 3-1 in Jeddah.
Cerezo and Jeonbuk had met twice in the group stage earlier in the year.
Both resulted in 1-0 home wins, but Wednesday's contest was a much more open and entertaining game.
Jeonbuk deservedly led 2-1 at half-time, having played enterprising football in a competition where the visiting sides usually take few risks.
South Korean international striker Lee Dong-gook scored both goals for the visitors, the second through a lucky deflection right on the stroke of half-time.
Ryuji Bando had netted the first of three equalisers for Cerezo when he prodded home a Kim Bo-kyung cross.
Hiroshi Kiyotake - a recent addition to Japan's national team - scored the second equaliser, heading home a corner in the 55th minute.
However Jeonbuk almost immediately went back ahead through captain Cho Sung-hwan, who also headed in a corner.
Kim scored a penalty for Cerezo to make it 3-3, and Kiyotake scored the winner in the 82nd minute, drilling home a low shot from a corner.
In Suwon, the Bluewings paid the price for missing several chances and were held at home by Zob Ahan.
The Iranian club was content to sit back and try to get an away goal on the counter-attack and that is precisely what happened 10 minutes into the second half, as Igor Castro got behind the defence and set up Mohammad Ghazi to score from close range.
Suwon's impressive record of not having lost in 26 straight home games in continental competition was in jeopardy until Park Hyun-beom volleyed in an equaliser ten minutes later.
The return legs will be played on September 27-28 and the eventual champion will earn a place in the Club World Cup.