This paper presents a universal output-feedback tracking strategy for minimum phase linear systems of arbitrary but known relative degree with a class of nonlinear perturbations and output measurement noises. Some information, such as the state dimension, the sign of high-frequency gain and the relative degree of nonlinearly perturbed systems, are not known a priori. It is proved that the tracking error is guaranteed asymptotic to the interval [-lambda, lambda] subset of R with arbitrary prescribed lambda > 0.