  I use the two-step density-matrix renormalization group method based on
two-leg ladder expansion to show numerical evidence of a plaquette ground state
for $J_2=1.3J_1$ in the Shastry-Sutherland model. I argue that the DMRG method
is very efficient in the strong frustration regime of two-dimensional spin
models where a spin-Peierls ground state is expected to occur. It is thus
complementary to quantum Monte Carlo algorithms, which are known to work well
in the small frustration regime but which are plagued by the sign problem in
the strong frustration regime.
