The present invention relates to a cascade process for the preparation of a graft copolymer comprising a polyolefin main chain and one or a multiple polymer side chains. The process comprising step A) of copolymerizing at least one first type of olefin monomer and at least one second type of metal-pacified functionalized olefin monomer using a catalyst system to obtain a polyolefin main chain having one or multiple metal-pacified functionalized short chain branches, the catalyst system comprising: i) a metal catalyst or metal catalyst precursor comprising a metal from Group 3-10 of the IUPAC Periodic Table of elements; and ii) optionally a co-catalyst; and step B) of forming one or multiple polymer side chains on the polyolefin main chain having one or multiple metal-pacified functionalized short chain branches to obtain the graft copolymer.