Lopetegui lasted four and a half months before being axed by Madrid last October following a heavy 5-1 loss to bitter rivals Barcelona.
The 53-year-old took just 14 points from a possible 30 during his time in the Spanish capital but has had far more joy at Sevilla since his appointment in June.
Sevilla are two points better off than Madrid ahead of Sunday's clash at Ramon Sanchez-Pizjuan, but Lopetegui claims he is not out for revenge against his former side.
"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."
Sevilla have won three and drawn one of their opening four matches and maintained their momentum with a 3-0 Europa League win at Qarabag on Thursday.
Lopetegui is refusing to look too far ahead, though.
"I do not focus on what I hope or don't hope for, but on the day-to-day and on preparing each game well," he said.
"We look at the very short term. It is the best way of using the energy we have as coaches.
"We know that in front of us there is an extraordinary team, with spectacular talent, that will force us to give our best version.
"I would like to see a Sevilla side that knows how to attack and defend well.
"We want the three points and we will go for the three points."