Demba Ba's agent says that his client "does not understand the management" of Newcastle after starting the 2-2 draw with Everton on the bench.
The 27-year-old forward came on to score both his side's goals, saying later he was unhappy at being named as a substitute by manager Alan Pardew.
"Since returning from the Africa Cup of Nations, Demba doesn't understand the management," said Alex Gontran.
"If he continues to be a substitute all season, we'll look at other solutions."