There may be more to the grudge between 49ers receiver Michael Crabtree and Seahawks cornerback Richard Sherman than what we saw on the field.

Sherman’s older brother, Branton, told Jerry Brewer of the Seattle Times that it was Crabtree who started the animosity between the two of them, several months ago. Branton Sherman says that both Richard Sherman and Crabtree attended Cardinals receiver Larry Fitzgerald’s charity event over the summer, and that when Sherman approached Crabtree to shake his hand, Crabtree tried to start a fight.

According to the report, Sherman’s response to that was, “I’m going to make a play and embarrass him.”