We report on observations from the Interball-Tail satellite of a long-lived sunward flowing plasma layer (SFPL), adjacent to the plasma mantle and affecting the high-latitude dawn northern lobe, well beyond the terminator. This observation pertains to periods when the interplanetary magnetic field was oriented mainly dawnward and northward or slightly southward. Although a plasma sheet origin of the SFPL cannot be completely excluded, we show that the most plausible source of the observed plasma is the magnetosheath. Possible entry mechanisms and entry sites are discussed. We show that the magnetosheath ions and electrons can enter the northern lobe via a rotational discontinuity (RD) affecting the high-latitude magnetopause tailward of the spacecraft location. Such a discontinuity is expected to result from the tailward convection of field lines reconnected at the dayside magnetopause. However, although the distribution functions of ions in the SFPL well fit the general entry mechanisms through RDs, the electron component is clearly heated and accelerated. Their characteristics appeal for specific acceleration and heating mechanisms related to the intrinsic structure of a RD. ¿ 2001 American Geophysical Union