MELBOURNE (AFP) - Rowdy behaviour at the Australian Open came under scrutiny for a second day running on Friday (Jan 21) and again it involved Nick Kyrgios, with an Olympic champion saying the crowd lacked "respect".

Russian second seed Daniil Medvedev took aim at sections of the Rod Laver Arena on Thursday after beating the Australian showman Kyrgios, saying some home fans had "low IQ".

On Friday, it was the turn of Croatians Nikola Mektic and Mate Pavic to complain after the top men's doubles seeds suffered a shock 7-6 (10/8), 6-3 loss to Kyrgios and fellow Australian Thanasi Kokkinakis.

"They are pretty loud, obviously they cheer for Aussies. It wouldn't hurt them to show some respect to all opponents, to other players," said an unamused Pavic, who won gold with Mektic at the Tokyo Olympics.

"We saw yesterday also with Medvedev how it was. That's how they are here, we're used to that.

"But like I said, it wouldn't hurt them to show some respect."

Mektic had praise though for the Australian duo, saying: "The guys played really well. They're a nasty team to beat here and that's it."

The unpredictable Kyrgios was at his colourful best in defeat to Medvedev, dealing out all his assortment of underarm serves and tweeners before a partisan home crowd while embroiled in a running battle with the chair umpire.

He defending his antics afterwards, saying: "That's why the crowd is the way it is, that's why the tickets are the way they are, that's why the views are the way they are."