Tennis, or at least front row seats at a grand slam, brought two old political rivals together - and left-wing Twitter users are seeing red. 

A photo of Labor Prime Minister Anthony Albanese sitting next to former Liberal treasurer Peter Costello at the Australian Open women's final on Saturday night in Melbourne sparked anger from the PM's supporters on the social media platform. 

Mr Albanese and Mr Costello looked very relaxed in each other's company as they watched Belarusian Aryna Sabalenka win her first major against Elena Rybakina.

Twitter users were anything but relaxed about the situation.

'Reports of Albo cosying up to Peter Costello at the tennis makes me really uncomfortable,' one wrote.

'Look I'm cracking the sh**s because he was sitting next to Peter Costello,' another said candidly. 

'You know what? I'm unsurprised. It makes me feel more than uncomfortable; it makes me feel nauseous,' said another.

'Your skin would crawl,' another wrote. 

Quite a few harked back to an old quote of Mr Albanese's that he likes 'fighting Tories (conservatives). That's what I do.'  

'Albo sitting with Peter Costello at the tennis. This is what fighting Tories looks like, I guess?' one Twitter user sarcastically noted.

A few were quick to read political significance into the seating arrangement. 

'More proof Labor has become LNP lite...Also why was Albo sitting next to Peter Costello at the Women's tennis final?' one wrote. 

Some tried to rationalise Mr Albanese's actions. 

'My mother always said 'Keep your friends close, and your enemies closer' I like to think this is what he is doing,' wrote one Twitter user. 

A number of people noted that Mr Costello, who was treasurer during the Howard government from 1996 to 2007, still holds important positions such as chair of Australian Open broadcaster Nine and also the publicly owned Future Fund.

Mr Albanese, who is a keen social tennis player, was back at the Australian Open on Sunday night for the men's final along with his partner Jodie Haydon.

Mr Costello was back as well but this time he sat next to Opposition Leader Peter Dutton, while Mr Albanese was flanked by Tennis Australia Chair and Virgin CEO Jayne Hrdlicka. 

It was the third night that Mr Albanese had taken his place in the stands of Rod Laver as he attended Friday night as well for the men's semi-final between American Tommy Paul and eventual tournament winner Novak Djokovic.