Depends what we mean by at the highest level? Do you mean within a top tier club competition (I.e. Top 14, URC, Premiership, Super Rugby). Do we exclude MLR and Japan Rugby League One?

Stormers currently have one of these players, but he never made it to the Springboks. Brok Harris is currently 40 and has been playing club rugby since 2005. He was meant to come to the Stormers just to be a coach, but then we had a player shortage due to injuries and he has played four more years. He generally is on the bench, but still has semi-regular starts for us.

Our next closest player is Deon Fourie who turns 39 this year and has picked up test matches for the Springboks and was part of the last World Cup, and technically was the on field captain when we won the final. He might make it to playing at 40, but I do wonder if he will make it as he has picked up some injuries in the last year and a half.