We present the partial branching fraction for inclusive charmless semileptonic B decays and the corresponding value of the Cabibbo-Kobayashi- Maskawa matrix element |Vub|, using a multivariate analysis method to access ∼90% of the B→Xu ν phase space. This approach dramatically reduces the theoretical uncertainties from the b-quark mass and nonperturbative QCD compared to all previous inclusive measurements. The results are based on a sample of 657×106 BB̄ pairs collected with the Belle detector. We find that ΔB(B→Xu ν;p *B>1.0GeV/c)=1. 963×(1±0.088stat±0.081syst)×10-3. Corresponding values of |Vub| are extracted using several theoretical calculations.