Semi-finalist Khachanov defends Australian Open 'Artsakh' messages
The Russian, who has Armenian roots, wrote a message on a television camera lens after his fourth-round win at Melbourne Park that said: "Keep believing until the very end. Artsakh, hold on!"
In a previous round, the semi-finalist wrote: "Artsakh stay strong."
They were referencing the contested region of Nagorno-Karabakh, an Armenian-populated enclave of Azerbaijan over which Baku and Yerevan have fought two wars.
"I have Armenian roots. From my father's side, from my grandfather's side, even from my mum's side. I'm half-Armenian," he said after reaching the semi-finals, with an Armenian flag seen in Rod Laver Arena.
"To be honest, I don't want to go deeper than that and I just wanted to show strength and support to my people. That's it."
In a letter posted online, the Azerbaijan Tennis Federation said it had protested to Australian Open organisers and the International Tennis Federation (ITF).
It demanded he be "punished" with "harsh measures".
"Writing heartfelt wishes on the camera lens is a kind of tradition in tennis but Khachanov abused this, using it in his dirty plans," it added.
Khachanov said he was not aware of the letter and had not been told to stop his post-match messages "so far".