The Australian Open is using the new Hawk-Eye electronic line-calling system rather than line umpires. It is a sensible move given Covid-19 restrictions, although there is a possibility of an unexpected option beyond out and fault, advertisements.

Advertisements in papers and on TV are a regular part of life and there are so many logos on players' uniforms. Surely enough brands are out there for anyone to want, but apparently no.

The line-calling system may now call out buy brand X or brand Y will make your skin glow or if it is connected by Wi-Fi, there are many other messages that an enthusiastic hacker could call out and have heard by the whole world.

This could be the new version of Trump Twitter posts now that his voice is silenced for a while. Again, a good use of science that can be misused and abused by big business.

Dennis Fitzgerald, Melbourne, Australia