Goals from Asahi Uenaka and Jun Amano in four second-half minutes earned Steve Holland s side victory in Pudong Stadium but the line-up for next month s knockout rounds remains uncertain after Shandong pulled out of the competition.

The withdrawal, which Shandong claimed was due to health issues within their squad, was announced by the Asian Football Confederation hours before the Chinese side were due to face South Korea s Ulsan HD in their final match.

Shandong s decision to pull out means all of the club s results in this season s tournament have been annulled as per the competition s regulations.

That has cast an air of uncertainty over the final league phase table for east Asia and, with it, the pairings for the next round of the competition.

Under the Swiss league system, which was introduced this season as part of a major overhaul, the team finishing top of the standings will take on the eighth placed side, second place will play seventh and so on.

But with Shandong s results expunged, three clubs -- Buriram United, Shanghai Shenhua and Shanghai Port -- have earned points across eight matches compared to seven for the remaining teams in the competition.

The AFC has said the matter will be referred to the relevant committees "as appropriate for their decisions".

No timeline has been given regarding when a decision will be made, with the first leg matches in the last 16 due to be played on March 4 and 5. The returns are a week later.

The uncertainty had no bearing on Yokohama s performance, however, as last season s runners-up dominated in Shanghai.

Home goalkeeper Yan Junling made a string of saves to deny the Japanese club until Uenaka thumped a rising shot beyond the goalkeeper in the 64th minute.

Amano doubled the lead four minutes later when he chested in Kanta Inoue s cross from the right to earn Marinos a deserved victory.

Despite the loss, Shanghai Port finished inside the top eight, just below compatriots Shanghai Shenhua, but the final outcome remains to be confirmed.