Task: Explanation
Input (English): Sergio Gabriel Martínez (born February 21, 1975) is an Argentine former professional boxer who competed from 1997 to 2014. He held the unified WBC, WBO, "Ring" magazine, and lineal middleweight titles between 2010 and 2014, making six successful defenses of the latter two titles. Martínez's 50-month reign as lineal champion ranks as one of the longest in middleweight history. He also fought at light middleweight, where he held the IBO title from 2003 to 2005, and the WBC interim title in 2008 (later elevated to full world champion status the following year). Question: Who reigned for 50 months as lineal champion  and fought Richard Williams? Answer: Sergio Gabriel Martínez
Output (English): Sergio Gabriel Martínez born February 21, 1975 is an Argentine former professional boxer who competed from 1997 to 2014.