The South Korean footballer Ki Sung-yeung has sparked a row with Japan amid accusations that he directed a racist gesture at Japanese fans during the countries' Asian Cup semi-final this week.
Replays of the match, which Japan won on penalties, show Ki pulling a monkey face after opening the scoring against Japan, South Korea's fiercest football rival.
The gesture is viewed as insulting towards the Japanese, the Korean peninsula's colonial rulers for 35 years until the end of the second world war.
The Celtic forward later said he had intended to highlight racism in the Scottish game after he and another South Korean footballer were subjected to monkey chants during a Scottish Premier League match this season.
But his explanation has failed to convince the Japanese: TV news shows broadcast endless repeats of the goal celebration and feelings were running high online.
Several posters cited comments Ki made after the match as proof that his insult had been directed at Japanese fans; others wondered why he had chosen a match between two Asian teams playing in Qatar to respond to Scottish football supporters.
Ki said that when he spotted a rising sun flag in the stands at al-Gharafa Stadium in Doha, Qatar, "my heart shed tears. I think of myself as a Korean first and a soccer player second."
One poster responded: "[If] being a Korean is more important that being a soccer player ... then get off the soccer field you moron."
Ki was apparently referring to the flag version showing a radiating sun that was used by Japanese imperial forces before and during the war. Many in Japan insist the flag was not on display inside the stadium.
Despite strong trade and people-to-people ties some South Koreans have never forgiven Japan for its wartime conduct. The countries have yet to resolve a longstanding territorial dispute and reconcile over the Japanese army's use of tens of thousands of Korean women as sex slaves before and during the war.
Ged Grebby, chief executive of the Show Racism the Red Card campaign, questioned Ki's explanation. "It doesn't ring true to me that that's what it was about."
Ki appears to have been referring to Celtic's 3-0 win over St Johnstone last October. After the game the Perth club said it was launching an investigation into claims that Celtic players had been subjected to "racist noises".
Ki's compatriot and Celtic teammate, Cha Du-ri, said: "When Ki had the ball two supporters jumped up and started making monkey noises in unison. I played for eight years in Germany and I have never seen anything like that."
A spokesman for the Korea Football Association supported Ki's version of events. "The treatment he got from the Scottish league, especially in the away games ... that is something he wanted to highlight.
"Even though they call him a monkey because he's Asian, he wanted to show how strong they are in Asia. That was the main intention."
Japanese football accepted the explanation and the Asian Football Confederation said it would not be taking action. "We are aware of the goal celebration but we don't think it impacts on any country," said AFC tournament director Tokuaki Suzuki.
Japan will play Australia in the final on Saturday.