In pulsed magnetic fields up to 65T and at temperatures below the Néel transition, our magnetization and magnetostriction measurements reveal a field-induced metamagnetic-like transition that is suggestive of an antiferromagnetic to ferrimagnetic ordering. Our data also suggests a change in the nature of this metamagnetic-like transition from second-to first-orderlike near a tricritical point at T tc ~145K and H c~5 2T. At high fields for H>H c we found a decreased magnetic moment roughly half of the moment determined by neutron powder diffraction. We propose that the decreased moment and lack of saturation at high fields indicate the presence of a field-induced ferrimagnetic state above the tricritical point of the H-T phase diagram for USb 2 .