Complex sentence: Early in the third round Grimaud took Taylor's back, as Taylor was attempting to escape back control Grimaud trapped Taylor's arm and transitioned to an armbar forcing Taylor to submit, thus retaining his welterweight title.
Split into simpler sentences: Early in the third round Grimaud took Taylor's back. As Taylor was attempting to escape back control, Grimaud trapped Taylor's arm and transitioned to an armbar, forcing Taylor to submit and thus retaining his welterweight title.