  In this paper, we consider the Yang-Mills heat flow on $\mathbb R^d \times
SO(d)$ with $d \ge 11$. Under a certain symmetry preserved by the flow, the
Yang-Mills equation can be reduced to: $$ \partial_t u =\partial_r^2 u
+\frac{d+1}{r} \partial_r u -3(d-2) u^2 - (d-2) r^2 u^3, \text{ and } (r,t) \in
\mathbb R_+ \times \mathbb R_+. $$ We are interested in describing the
singularity formation of this parabolic equation. We construct non-self-similar
blowup solutions for $d \ge 11$ and prove that the asymptotic of the solution
is of the form $$ u(r,t) \sim \frac{1}{\lambda_\ell(t)} \mathcal{Q} \left(
\frac{r}{\sqrt{\lambda_\ell (t)}} \right), \text{ as } t \to T ,$$ where
$\mathcal{Q}$ is the ground state with boundary conditions $\mathcal{Q}(0)=-1,
\mathcal{Q}'(0)=0$ and the blowup speed $\lambda_\ell$ verifies $$\lambda_\ell
(t) = \left( C(u_0) +o_{t\to T}(1) \right) (T-t)^{\frac{2\ell }{\alpha}} \text{
as } t \to T,~~ \ell \in \mathbb{N}^*_+, ~~\alpha>1.$$ In particular, when
$\ell = 1$, this asymptotic is stable whereas for $ \ell \ge 2$ it becomes
stable on a space of codimension $\ell-1$. Our approach here is not based on
energy estimates but on a careful construction of time dependent eigenvectors
and eigenvalues combined with maximum principle and semigroup pointwise
estimates.
