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We theoretically investigate the high-order above-threshold ionization (HATI) of an atom in an infrared (IR) and extreme ultraviolet (XUV) two-color laser field, where the XUV photon energy is much larger than the atomic ionization threshold.The HATI spectrum presents a multi-plateau structure, where the height of each plateau is determined by how many XUV photons is absorbed by the atom.By analyzing the XUV multi-photon quantum channels, we find that the ionized electron can collide with its parent ion elastically and non-elastically.Especially, in the non-elastic channel, the ionized electron absorbs XUV photons during the collision, which cannot be explained by the classical three-step model.Our results indicate that the previously established concept that "HATI is an elastic recollision process" breaks down.