We discuss how several different theories can lie in the same universality class at a fixed point due to a common interaction in the Lagrangian. This equivalence occurs at the non-trivial fixed point of the respective beta functions. Six-dimensional QCD has recently been renormalised at two loops in the modified minimal subtraction scheme. Using the large Nf expansion, it has been shown that six-dimensional QCD lies in the same universality class as the two-dimensional non-abelian Thirring model. Following this, we would now like to consider QCD in eight dimensions and renormalise it at one loop. This requires the construction of the eight-dimensional QCD Lagrangian in a linear covariant gauge. We do this by finding a basis of linearly independent gauge invariant operators of dimension eight.