Question: Who did the professional tennis player currently ranked World No. 1 in men's singles defeat in the 2017 Barcelona Open Banco Sabadell - Singles?
Sentence (from "2017 Barcelona Open Banco Sabadell – Singles"): Rafael Nadal was the defending champion and successfully defended his title, defeating Dominic Thiem in the final, 6–4, 6–1.
Relevant evidence: Yes