Benzema headed the champions in front on the hour mark while French left-back Mendy doubled their lead six minutes later, starting the move with a bursting run through midfield before sliding in to knock home a cross from Marcelo.
The victory took Zinedine Zidane’s side into second in the standings and left them five points below Atletico, who drew 2-2 with Celta Vigo on Monday to end an eight-game winning streak. Diego Simeone’s league leaders have two games in hand over their chasing rivals.
“This win gives us a lot of confidence, I think we are on our way back to our best,” said Benzema.
“Getafe always make things difficult for you but we put in a big performance. We’re just focusing on ourselves, we’re not looking at the league table but we’re going to try to win every game because there’s still a long way to go in the season.”
Real were missing nine first-team players through injury or suspension, which led Zidane to field an unorthodox 3-4-3 formation, while handing 20-year-old midfielder Marvin Park his first start for the club and giving defender Victor Chust his league debut from the bench.
Of their pursuit of Atleti atop La Liga, Zidane said: “Nothing will change. We’ll do our thing. There are 51 points left. We’ll keep going, I said the same thing a week ago, we have to fight, keep doing our job, without focusing on the rest. It’s a good victory, two in a row, we needed it, with a lot of absentees too. We have to carry on now.
“I don’t think there are Madridistas who think we can’t win the league. It’s the opposite, they always think we can change things, that’s what we’ll try to do. With difficulties of course, but we’ll keep going, believing in what we do. There’s a lot ahead of us.”