Notwithstanding this powerful support, Nanni di Baccio Bigio kept trying to eject him from his post.

He wrote to the Grand Duke in 1562, arguing that Buonarroti was in his dotage, and begging Cosimo to use his influence to obtain the place for himself.

In reply the Grand Duke told Nanni that he could not think of doing such a thing during Michelangelo's lifetime, but that after his death he would render what aid was in his power.

An incident happened in 1563 which enabled Nanni to give his enemy some real annoyance.

Michelangelo was now so old that he felt obliged to leave the personal superintendence of the operations at S.Peter's to a clerk of the works.