Very steep waves constitute an essentially nonlinear and complicated phenomenon. Inter-related experimental and theoretical efforts are thus required to gain a better understanding of their generation and propagation mechanisms. A nonlinear focusing process in which a single unidirectional steep wave emerges from an initially wide amplitude- and frequency-modulated wave group at a predicted position in the laboratory wave tank is studied both theoretically and experimentally. The spatial version of the Zakharov equation was applied in the numerical simulations. Experiments were carried out in the 330 m long Large Wave Channel (GWK) in Hannover, Germany and in the 18m long Tel-Aviv University (TAU) wave tank. Quantitative comparison between the experimental and the corresponding numerical results is carried out. Good agreement is obtained between experiments and computations.