Question: Which tennis player won a major tennis championship in singles, Juan Martín del Potro or Bob Bryan?
Sentence (from "Juan Martín del Potro"): Juan Martín del Potro (] , born 23 September 1988), also known as Delpo is an Argentinian professional tennis player who is currently ranked world No. 24 in men's singles by the Association of Tennis Professionals (ATP).
Relevant evidence: Yes