Sebastian Baez defeated Juan Pablo Varillas in the quarter-finals of the Buenos Aires CH, an ATP Challenger event played on clay on 23 October 2021. Baez advanced through the draw in what represented a solid performance on home soil for the Argentine player. The result underscored Baez's competitive standing in the Challenger circuit at that stage of his career, as he continued his push towards the semi-finals in Buenos Aires. This victory kept Baez's title hopes alive in his native country.