Yaya Toure's agent, Dimitri Seluk, told BBC Sport that his client is "very upset" about the lack of respect that the team's owners showed him on his special day, even though he received a birthday cake and a shout-out on Twitter.
"None of them shook his hand on his birthday. It's really sick. He got a cake but when it was Roberto Carlos's birthday, the president of Anzhi gave him a Bugatti," Seluk told BBC Sport.
"I don't expect City to present Yaya with a Bugatti, we only asked that they shook his hand and said 'we congratulate you.' It is the minimum they must do when it is his birthday and the squad is all together."
Toure backed up Seluk's remarks on Twitter.
Thanks for all the birthday messages today. Card from City just arrived... Must have got lost in the post. Haha— yaya toure (@Toure_yaya42) May 20, 2014
Everything dimitry said is true . He speaks for me . I will give an interview after world cup to explain— yaya toure (@Toure_yaya42) May 20, 2014
The team signed Toure to a four-year contract last summer, but it certainly sounds as if his future with City is in doubt.
"Of course Yaya is upset about this. If this happened to you as a journalist in the BBC and nobody shakes your hand, you will say bye-bye and go to work for somebody else. It is normal," Seluk said. "The most important thing is a human relationship and maybe this is his opportunity for Yaya to find that. If City don't respect him, then, easy, Yaya will leave. No problem."