  We investigate the competition between pairing correlations and
ferromagnetism in small metallic grains in the presence of a Zeeman field. Our
analysis is based on the universal Hamiltonian, valid in the limit of large
Thouless conductance. We show that the coexistence regime of superconducting
and ferromagnetic correlations can be made experimentally accessible by tuning
an external Zeeman field. We compare the exact solution of the model with a
mean-field theory and find that the latter cannot describe pairing correlations
in the intermediate regime. We also study the occurrence of spin jumps across
the phase boundary separating the superconducting and coexistence regimes.
