Sydney FC have been punished for a slow start against Yokohama F Marinos, and now require a perfect finish to their Asian Champions League group to reach the knock-out stages.
Steve Corica's side conceded two early goals and though their Japanese opponents were reduced to ten men just after the hour-mark could not get back into the game. Instead they conceded again.
Later in Vietnam's Ho Chi Minh City, where the group H round-robin is being staged, Jeonbuk drew 1-1 wth hosts Hoang Anh Gia Lai.
That left the South Korean side six points ahead of Sydney with two matches remaining. Sydney must now beat Jeonbuk on Thursday, and Hoang Anh Gia Lai on Sunday, while hoping Kevin Muscat's table-topping Yokohama also defeat Jeonbuk.
Then they must hope they are one of the three best runners-up of the East Region's five groups.
"We lost the game after ten minutes," said Corica. "We had a slow start and going two-nil down it was always going to be hard to come back into it.
"It was a poor first half performance but a lot better in the second half and we again create two or three very good chances which we didn't take.
"At least we had a good crack in the second half and it was much better. We conceded late as everyone pushed forward."
Yuki Saneto's sixth-minute diving header and Takuma Nishimura's neat finish after 11 minutes gave the Japanese club the half-time lead. The exit of Ryotaro Tsunoda for a professional foul on Pat Wood after 64 minutes gave Sydney hope, but substitutes Bobo and Trent Buhagiar both missed chances to cut the deficit.
With three minutes left Lopes killed off any chance of a comeback with Yokohama's third.
Results against the bottom club in each group will be discounted from the runners-up calculation after Shanghai Port were forced to withdraw from Group J due to COVID-19 restrictions in China.
