News Corp Australia’s flagship masthead has served the gold-medal-winning South Australian teenager with a strange slapdown, with an article and editorial bemoaning that he evidently didn’t sing the national anthem with the requisite gusto.

“He appeared to have forgotten the words to Advance Australia Fair,” wrote the paper’s sports editor, Wally Mason.

“He seemed to mumble the first few bars but then gave it away.”

Mason similarly chided Australia’s day-one gold medalist Mack Horton for not singing along, while “the athletes of other nations sing their anthems loud and clear, signalling their national and personal pride”.

“American swimmers, in particular, all know the words [to the] Star Spangled Banner and sing with enthusiasm,” he wrote, arguing that Australian chef de mission Kitty Chiller “would do well to hand out song sheets and singing lessons so that when next an Australian collects a gold medal, the athlete, and the millions of Australians watching, can sing the anthem with pride”.

But the Oz didn’t stop there, with an editorial headlined “Sing up, Olympic champions” bemoaning that “we wish our gold medallists would sing up with the pride and patriotism most US athletes exude as they belt out the Star-Spangled Banner, hands on hearts”.

“The swimmers are our most successful champions so far… but Kyle Chalmers, Mack Horton and others either didn’t want to sing on the dais or didn’t know the words,” the editorial moped.

The Australian’s campaign appeared to fall flat on social media, with several Twitter followers berating the paper’s account for attacking the Olympic heroes.

I've read it all now. Apparently winning gold for Aust not enough, you've got to ham up the anthem too https://t.co/wPevci7lpU

— Daniel Brettig ? (@danbrettig) August 11, 2016

Re Kyle Chandler: 1, win the 100m from nowhere, you can break dance to the anthem for all I care; 2, silence during anthem more dignified.

— Virginia Trioli (@LaTrioli) August 11, 2016

https://twitter.com/JamColley/status/763873830288789505

https://twitter.com/KerbstompAu/status/763882101414371328

To a tweet from the paper’s Canberra correspondent David Crowe on the subject, one reader responded that Chalmers “probably hasn’t forgotten words but just taking in [the] awe of the moment”.

Crowe replied: “Fair point. Had us talking in the office yesterday though. Strong opinions on the anthem.”

SA’s Opposition Leader Steven Marshall – like Chalmers, an Immanuel alumnus – told InDaily: “Kyle Chalmers is a champion and yesterday’s performance indicates he’s going to get plenty of chances to sing our national anthem. That swim was absolutely amazing.”

Asked whether Chalmers should have sung the anthem with more gusto, Premier Jay Weatherill simply said: “I couldn’t have been any more proud.”