They're knee-high, worth thousands of dollars and have excellent soccer skills.
The are not child sports prodigies, but rather some of the high-tech, humanoid robots battling it out at the 2019 RoboCup world championships, the world's largest annual robotics competition.
Held for the first time in Sydney this year, the event brings together competitors from more than 40 countries, with the aim of promoting robotics and artificial intelligence research and development.
Robots of all shapes and sizes - including full human size - will compete over four days at the International Convention Centre in events including robot soccer, search-and-rescue missions, manufacturing and logistics as well as home assistance challenges.
Sydney's own University of NSW's Runswift team secured an early win on the first day of competition on Thursday, scoring four goals to nil against the Camelia Dragons from Japan in a game of five-a-side robot soccer.
With names like Legolas, Nemo and Dory, the "Nao" robots stand about 60 centimetres high and are worth up to $13,000 each.
UNSW's team is in the standard platform league, in which competitors use the same hardware - such as the motors, computer, cameras, and pressure sensors for balance - but develop their own software program to give themselves an advantage.
UNSW professor of computer science and engineering and RoboCup 2019 chair Claude Sammut said the robots act completely autonomously during the game.
Once the whistle blows, "they're on their own," Prof Sammut told AAP on Thursday.
The robots have in their head a little board which is a computer "no more powerful than (a) mobile phone" and communicate with their fellow players via a wifi network, Prof Sammut said.
The robots keep "maps" in their head which they exchange via this network so they know where each of their teammates is on the field, he said.
Unlike in real soccer leagues, at the end of the competition, the top teams publish all of their code.
"Although we're competing, we also want to collaborate in the sense that we want to push the technology forward," Prof Sammut said.
There are real-world applications for the kind of technology being used at RoboCup.
Some recent UNSW graduates have gone onto work for companies developing self-driving cars, and say their work on the competition translates.
"Even though it's not playing soccer, all the techniques and the way they program the robots carry across," Prof Sammut said.
UNSW is also working with a start-up company in Sydney which is building autonomous sailing boats intended to be used for surveillance in the wide ocean for purposes such as defence or environmental monitoring.
