 Complete the following phrase:  The company decided to make Estrada the next Mexican National Middleweight Champion, which happened on March 4, 1984, when he defeated Ultraman. Over the subsequent 273 days, he successfully defended the championship against Águila Solitaria, Cachorro Mendoza, Atlantis, and Mogur. Estrada was slated to wrestle at the EMLL 52nd Anniversary Show on September 20, but it was canceled due to the 