This article investigates how anchor firms sustain high tech clusters rejuvenation by means of technological pre-adaptation. Based on evidences are drawn from the comparison of the evolution of two nano-electronics clusters, i.e., Grenoble (France) and Catania (Italy) clusters which are sharing the same anchor tenant firm STMicroelectronics. Cluster rejuvenation comes from pre-adaptation of actors (scientific and technological diversity), competition amongst anchor tenant firms, competition and overlap amongst networks and the mobilization of sleeping anchors tenant organizations to renew actors and technologies. As soon as the process of specialization (asset specificity, network specificity, technology speciation) starts, it is important to stimulate pre-adaptation to avoid lock-in of the cluster on one technological trajectory