Lopetegui lasted four and a half months before being axed by Madrid last October following a heavy 5-1 defeat to bitter rivals Barcelona.
"There is no room for extra motivation when you coach Sevilla, something I can hopefully do for many years," he said. "There are three points at stake and that is enough motivation, even if we know the impact of facing Real Madrid.
"I always have a very good memory of all the clubs where I have been, as I stay with the positive. I try to be responsible and ambitious, and [Sunday] will be no exception. The central characters are the players, not the coaches."