The South African born duo are very close off the field but Errie admits brotherly love will be in short supply when they meet under the floodlights at Sixways.
"Michael does like to tell me every day that he is going to tackle me hard when he meets me," smiled Errie. "Luckily, I am the older brother, though, so I should have the age advantage!
"We are quite close, with only a year difference between us and he is pleased to see me playing in the Aviva Premiership.
"We actually see each other once every couple of weeks and I watch his games if I can.
"It's good to be in the same league at last and we have got a lot in common as we do the same job."
Watch the Claassens brothers go head-to-head at Sixways! Tickets are still available by calling the Warriors Box Office on 01905 454183 or clicking HERE