The Asian Cup has suffered another blow to its credibility following a controversial penalty shootout involving Japan and Jordan.

Holders Japan won Saturday's quarter-final 4-3 on spot-kicks amid ugly scenes having persuaded the referee to switch ends after missing their first two penalties.

Furious that the referee agreed to Japanese protests about the condition of the penalty spot, Jordan promptly missed four of their six kicks at the other end.

Japan, held 1-1 by Jordan after extra-time, advanced to the semi-finals, where they face Bahrain.

Meanwhile, the Asian Football Confederation (AFC) faced further embarrassment following a troubled two weeks.

"Psychologically, if you are leading then you don't want to change ends suddenly," AFC general secretary Peter Velappan told Reuters on Sunday.

"I can understand why the Jordan players were upset. It's very unfortunate."

Already plagued by political rows and disciplinary problems, the 2004 Asian Cup threatened to descend into farce in Chongqing.

After Shunsuke Nakamura and Brazilian-born Alex had blazed over, the Japanese bench held up Jordan's second kick to protest about the condition of the turf around the penalty spot.

The shootout was delayed for at least five minutes as a furious row erupted between players, coaches and match officials.

During the confusion, Malaysian referee Subkhiddin Salleh ordered the teams to switch ends, further infuriating the Jordan players.

UNDER FIRE

After Bashar Bani Yaseen fired Jordan's seventh kick wide, Salleh came under fire from the Middle East side but the AFC has backed the referee.

"Two Japanese players drew his attention to the spot and he found that the turf was uplifted," Velappan said, who blamed the problem on a rainstorm.

"We had heavy rain before the match and that caused the problems," he said. "But it was the referee's discretion and his sole responsibility.

"We have had failing lights, floods, thunderstorms," Velappan added. "But nothing like this has happened before. We will have to look into it and inform FIFA. It's a learning experience."

Velappan denied that Japan had engaged in gamesmanship.

"Watching on television, I had that feeling when I saw the bench becoming involved," Velappan said. "But I go entirely by the referee's report and there was no influence from Japan."

However, Japan captain Tsuneyasu Miyamoto told reporters that he had convinced the referee to switch ends.

"(England captain) David Beckham did the same thing (against Portugal at Euro 2004)...and when England complained they were ignored," said Miyamoto. "I felt I had to try to convince the referee."