Question: The Men's 2013 US Open Series was won by which Spanish player, currently World #1?
Sentence (from "2013 US Open Series"): In tennis, the 2013 US Open Series (known as Emirates Airline US Open Series for sponsorships reasons) was the tenth edition of the US Open Series, which included ten hard court tournaments that started on July 20, 2013 in Atlanta and concluded in Winston-Salem for the men and in New Haven for the women on August 24, 2013.
Relevant evidence: No