Complex sentence: He later avenged this fight by knocking out Mike Weaver in two rounds and in 1989 challenged Francesco Damiani for the vacant WBO heavyweight title, (DuPlooy was Kayoed in the third round) in the World Boxing Organization's inaugural heavyweight world title bout.
Split into simpler sentences: He later avenged this defeat by knocking out Mike Weaver in two rounds and in 1989 challenged Francesco Damiani for the vacant WBO heavyweight title. Du Plooy was knocked out in the third round in the World Boxing Organization's inaugural heavyweight world title bout.