Illness forced Russian-born pianist Mark Zeltser to cancel his appearance Saturday night on the University Community Concerts series at the University of Maryland. He was replaced on a few hours' notice by Brazilian pianist Nelson Freire, who had just completed several concerts in the United States and was about to leave New York for Venezuela. Saturday's night's concert was Freire's third appearance in the Washington area.

Playing an all-Chopin program, Freire quickly dispelled any disappointed that the last-minute substitution may have caused. He is an intense, exciting pianist whose tone is big and warm. His interpretations were charged with energy, projecting a virile Chopin.

There was plenty of passion, for example, in his performace of the "Sonata in B Minor," but not one drop of sentimentality. In this work as in the others, he kept a relatively tight rein on tempos. Occasionally, some of the decorative passages were less brilliant than expected because Freire opted for a relentlessly driving tempo.

Throughout the evening Freire proved a master at bringing forth the subtle inner melodies and melodic fragments which are the key to much of the beauty in Chopin's music. Chopin has seldom seemed more alive and well than he did in Freire's hands Saturday night.