Sport president Frederico Varandas has confirmed that striker Viktor Gyokeres is confronted with disciplinary procedures at the club after he does not come to the training on Saturday.
Gyokees would go back on July 12 for training for the season, after the club gave him permission to postpone his return.
Arsenal has been in conversation to sign the 27-year-old, but has not reached an agreement on a £ 69 million deal so far.
Varandas said: “We are calm. Everything can be solved with the closure of the market, a big fine and an apology to the group.
“If they do not want to pay Viktor's real market value, we will be very comfortable with it for the next three years.
“If the geniuses that come up with this strategy think that this puts me pressure to make it easier for him to leave, they are not only completely wrong, but they also make it more complicated for the player to leave.
“Nobody is above the interests of the club. Whoever they are.”
Sport is supposed to want a first fee of £ 60.4 million, plus £ 8.6 million in add-ons.