What was the nationality of the WBA titleholder that Derrick Gainer lost to in a unanimous decision since his defeat to Juan Manuel Márquez?
Derrick Gainer:  Since his defeat to Marquez, Gainer lost in a challenge to WBA titleholder Chris John via unanimous decision. Chris John (boxer): Yohannes Christian "Chris" John (born September 14, 1979) is an Indonesian former professional boxer and world champion, who competed from 1998 to 2013.
Indonesian