A catalyst component formed by the steps of contacting a transition metal-containing metallocene of a transition metal of Group 4, 5 or 6 of the Periodic Table of the Elements with silica or an organic support. This product is contacted with an organomagnesium compound or complex followed by contact with an alcohol and a silane. Finally, the so-contacted product is contacted with a Group 4, 5 or. 6 transition metal-containing non-metallocene compound. The component is preferably combined with an aluminum-containing cocatalyst to form a catalyst system.