Bolton Wanderers striker El Hadji Diouf has been charged with improper conduct by The Football Association.
Diouf spat at Arjan De Zeeuw during the Bolton’s 1-0 home defeat to Portsmouth.
The 23-year-old has until Tuesday evening to answer the charge.
Bolton fined Diouf a maximum of two weeks wages on Sunday and could send him to a pyschological counseller.
“I deeply regret my actions and wish to apologise to Arjan de Zeeuw and Portsmouth,” said Diouf.
“My behaviour showed a lack of moral responsibility to the public who support me and I’m deeply sorry.”
A joint statement from chairman Phil Gartside and manager Sam Allardyce said: “The club does not tolerate such behaviour from its players.”
The statement continued: “We had no alternative but to evoke the maximum fine against El-Hadji Diouf.
“Bolton Wanderers takes great pride in its very proactive family image and yesterday’s incident has left a sour taste.
“We do not condone the actions taken by the player and for that he has been severely punished.”
De Zeeuw was taken aback by Diouf’s behaviour.
“I was a bit stunned at first. I thought ‘I can’t believe this’,” De Zeeuw said.
“But we were leading 1-0 and I was not going to get sent off for it even though I felt like punching him in the face.
“This shouldn’t happen. It is unsportsmanlike, ridiculous and cowardly.
“You would think after once he would have learned from it but apparently not. I am just very disappointed with him.”
Diouf was fined £5,000 at Glasgow Sheriff Court 14 months ago for committing the same offence against a Celtic fan during Liverpool’s encounter with the Scottish side.