This paper discusses the use of the so-called congelation of variables method in the reference tracking problem for a class of nonlinear systems with matched, time-varying, parametric uncertainty. It is shown that the tracking problem using the proposed framework can be decomposed into a zero-regulation problem and a disturbance rejection problem. To reduce the size of the disturbance term, a dynamical system with known input is incorporated into the parameter update law to generate a time-varying nominal parameter. To reject the remaining disturbance term, a sign-like function is exploited, which achieves an adjustable tracking performance in an average sense, while guaranteeing boundedness of all trajectories of the closed-loop system. The theory is illustrated by solving a path-tracking problem and it is shown that the proposed control scheme outperforms the classical scheme in the presence of time-varying parameters.