Quasars are believed to be powered by accretion of interstellar matter onto a super-massive black hole (SMBH) therein. Most of the observed energy is released in an accretion disk of inspiraling gas surrounding the SMBH. An enormous amount of fueling material, up to several tens solar masses per year, is expected to be transported inwards and consumed in the end. However, basic questions remain unanswered as to whether and how the accretion disks are supplied with external gas, since no disk-feeding inflow has hitherto been observed clearly. I will talk about the detection of redshifted broad absorption lines of hydrogen and helium atoms in a sample of quasars. The lines show broad ranges of Doppler velocities that extend continuously from zero to redshifts as high as 5,000 km/s. Such velocities are comparable to freefall speeds close to the black hole, constraining the fastest infalling gas to within 10,000 gravitational radii of the SMBH. Extensive photoionization modelling yields a characteristic radial distance of the inflow of approximately 1,000 gravitational radii, possibly overlapping with the outer accretion disk. Our results present the first compelling evidence for the long-sought inflow directly feeding quasars’ accretion disks with external mass, likely originating from the dusty torus at a parsec scale. Our approach provides a new tool to probe the bulk of the so far elusive fueling inflows in quasars. Their studies may help address some of the fundamental questions concerning accretion physics, the onset and sustainment of quasar activity, and the SMBH growth at centers of most galaxies.