The 31-year-old's frequent starts in the first team has fuelled speculation that Iker Casillas could leave the Santiago Bernabeu this summer.
However, Ancelotti has given his backing to Lopez and paid tribute to the stopper for his recent performances.
"Diego Lopez played the first game and now he has played the second game," Ancelotti told reporters.
"He is playing well at the moment. There is nothing more. The pressure is fuel to me [regarding the focus on the decision]."
Lopez rejoined Madrid in January from Sevilla.