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Theories of massive star formation predict that massive protostars accretegas through circumstellar disks. Although several cases have been found alreadythanks to high-angular resolution interferometry, it remains unknown theinternal physical structure of these disks and, in particular, whether theypresent warps or internal holes as observed in low-mass proto-planetary disks.Here, we report very high angular resolution observations of the H21alpha radiorecombination line carried out in Band 9 with the Atacama LargeMillimeter/submillimeter Array (beam of 80 mas x 60 mas, or 70 au x 50 au)toward the IRS2 massive young stellar object in the Monoceros R2 star-formingcluster. The H21alpha line shows maser amplification, which allows us to studythe kinematics and physical structure of the ionised gas around the massiveprotostar down to spatial scales of ~1-2 au. Our ALMA images and 3D radiativetransfer modelling reveal that the ionized gas around IRS2 is distributed in aKeplerian circumstellar disk and an expanding wind. The H21alpha emissioncentroids at velocities between -10 and 20 km s-1 deviate from the disk plane,suggesting a warping for the disk. This could be explained by the presence of asecondary object (a stellar companion or a massive planet) within the system.The ionized wind seems to be launched from the disk surface at distances ~11 aufrom the central star, consistent with magnetically-regulated disk wind models.This suggests a similar wind launching mechanism to that recently found forevolved massive stars such as MWC349A and MWC922.

The ionized warped disk and disk wind of the massive protostar Monoceros R2-IRS2 seen with ALMA