Swansea City manager Francesco Guidolin says Ki Sung-yueng's "attitude" was "not good" when he was substituted in their 1-0 defeat at Southampton.
The South Korea international midfielder looked unhappy and did not shake Guidolin's hand when he was replaced in the second half.
"This is not a good attitude. I have to speak with him," said Guidolin.
A week earlier the manager apologised to Neil Taylor after he was substituted in their 2-2 draw with Chelsea.
After losing at St Mary's and dropping to 15th in the Premier League, Guidolin denied players are unhappy with his management.
"I respect all people, all my players because the relationship is the most important thing for me.
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"In this league, in this squad I've found good, good guys. Good players - no problem for relationships.
"I can understand [Ki's disappointment], but it's not a good situation."
Guidolin admitted to being worried by his side not creating enough goal scoring chances.
Swans now face Premier League leaders Manchester City twice at Liberty Stadium this week.
They meet in the EFL Cup third round on Wednesday, then again in the Premier League on Saturday with Liverpool the next visitors to west Wales.
Guidolin has promised changes for the midweek cup match with Taylor already having been told he will be involved.
"It's impossible to play three games with the same line-up," said Guidolin, adding: "Neil Taylor will play on Wednesday."
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