With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Steffi Graf is a Leo.
text_B: Andy Murray was the defending champion , but lost in the quarterfinals to Juan Martin del Potro .. Andy Murray. Andy Murray. Juan Martin del Potro. Juan Martin del Potro. Roger Federer won the final against Rafael Nadal , 6 -- 4 , 6 -- 4 .. Roger Federer. Roger Federer. Rafael Nadal. Rafael Nadal. The semifinal match between Rafael Nadal and Novak Djokovic was at the time the longest men 's tennis match in the Open era played with the best-of-three system , stretching for 4 hours and 3 minutes with Nadal prevailing , 3 -- 6 , 7 -- 6 -LRB- 7 -- 5 -RRB- , 7 -- 6 -LRB- 11 -- 9 -RRB- .. Rafael Nadal. Rafael Nadal. Novak Djokovic. Novak Djokovic. best-of-three system. Tennis#Scoring. This record was later broken by Roger Federer and Juan Martin del Potro at the 2012 London Olympics in their 4-hour and 26 minute semifinal match .. Roger Federer. Roger Federer. Juan Martin del Potro. Juan Martin del Potro. 2012 London Olympics. Tennis at the 2012 Summer Olympics – Men's singles
not_related.