The spectacle is too good to ignore. Whether via YouTube, or in a park just off Sydney’s Darling Harbour, the sight of two dudes playing what looks like table tennis with their heads is irresistible to the eyeballs. The lunchtime crowd goes from strolling through to massing around the concrete-reinforced tables, ogling this suite of moves lifted from assorted penalty areas, rec rooms and keepy-uppy sessions.

The onlookers may think they’ve stumbled upon a novelty, but instead they’re being treated to a pair of the finest exponents of Headis – head tennis – in the world. More than that: they’re watching the inventor of the new sport, Rene Wegner, in action. He’s visiting Australia for the first time, hoping to parlay the Aussie willingness to play almost any sport into new Headists (that’s not the term they use, but it works). “When we come here first time on this nice continent, what we recognised here is people are so open – they like it, they take a picture. But then what happens here is people give it a go way earlier,” Wegner says.

He takes a swig of water. He’s sweating heavily in the unfamiliar humidity, but a rally of a dozen headers in a row will do that. Dial up video of a Headis tournament, and you’ll quickly notice there’s a lot of beer involved. But as Wegner notes, that’s for after the match: “You’ve just seen how we’ve played. You can’t do this wasted.”

The German accent is unmistakable, and it’s from that great footballing land that Headis hails. Wegner mentions that Jurgen Klopp is a fan, and it makes perfect sense – if the sport needed an avatar, it couldn’t do better than the Liverpool manager, who embodies a similar spirit of Teutonic madcap: frenetic, self-consciously eccentric and very, very fun. Klopp was rather taken with Headis when Wegner and company had a meet-and-greet at Klopp’s previous managerial post, Borussia Dortmund. Klopp also couldn’t help needling these funky kids about being from Kaiserslautern, rival to his old home club of Mainz.

If football-mad Germany was bound to seed something like Headis, then Kaiserslautern is key to its character. “If it was to come out of a German city, it had to be our city,” Wegner says. “There are a lot of Americans there because of the big air base. Skateboarding was very big growing up.”

The sense of innovation and casual cool of extreme sports have surely influenced Headis. The origin tale goes that back in 2007, Wegner and his uni friends wanted to play some football, but they couldn’t find an available field. The ping-pong tables, however, lay dormant. Soon enough, they had set themselves up with a table in an empty swimming pool, and had ditched using a soccer ball for what Wegner describes as “a Barbie-kind-of rubber ball off a little girl”.