With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Syd Barrett was only a guitarist for Metallica.
text_B: The Hoff Open is a tennis tournament held in Moscow , Russia since 2015 .. Moscow. Moscow. Russia. Russia. tennis. tennis. The event is part of the ATP Challenger Tour and is played on outdoor clay courts .. ATP Challenger Tour. ATP Challenger Tour
not_related.