For a class of single-input, single-output uncertain nonlinear systems affected both by uncertain constant parameters (with known bounds) and unknown time-varying bounded disturbances, a new robust adaptive output-feedback tracking control is presented. It is based on a reduced-order observer and guarantees input-to-state stability of the error system and almost disturbance decoupling of the tracking error with respect to disturbances and parameter estimation errors; asymptotic output tracking with arbitrary transient performance when disturbances are L-2 boolean AND L-infinity signals.