Per Yonhap, via the Daily Mail, a Korean Football Association spokesperson said: "It happened when some young players went up to play table tennis, and Son Heung-min and other older players took issue with it.
"The players exchanged a few words and Son hurt his finger in the process."
Lee has since apologised, issuing the following statement: "Good afternoon. This is Lee Kang-In. There is an article that I had a dispute with Son Heung-min before the 4th quarter of the Asian Cup.
"We are very disappointed for football fans who always support our national team. I am so sorry. I should have been in the forefront and obeyed my brothers, but I'm only sorry that I'm showing a bad side to football fans.
"I apologise to many of you who have disappointed me. I am well aware of the interest and expectations football fans send me. From now on, I will try to help my older brothers to become a better player and a better person."