Spin-up tracks of the accreting NSs leading to the final configuration rotating at f = 465 Hz and with gravitational mass M = 1.67 M_⊙ and magnetic field B = 2 × 10⁸ G. Curves are labeled by the average accretion rate (in M_⊙/yr and initial value of the magnetic field (in G). For comparison the spin-up for B = 0 (dashed line), via accretion from marginally stable orbit, is shown (color online).