Endrick struck the only goal of the night on Wednesday.
He said afterwards: "It was a difficult game, a Copa match that everyone wants to win. It’s not easy to play here, but we did what we came to do – win the game.
"We’re 0-1 up, which is great because the return leg is at home. We’re going back to Madrid to train hard for the next game against Betis. When the second leg comes around, we’ll go all out to win it because we want to get our hands on the Copa.
“I started the move off with a pass to Vini Jr., he laid it to Bellingham and I had space to run into. When he saw me, I made the run and he delivered the ball. I took it down well and shot with the outside of my boot.
"I think it was a really nice goal. I love scoring goals because I want to help the team but I can do that by scoring or running hard too. I’m thrilled to get the win and the goal.”
He added, “I’m a bit annoyed with the one that came back off the bar now because I could have done better. But that’s how I’ll improve, by looking at my mistakes and seeing what I can do better. I’m pleased I got the goal and we’re still chasing the Copa.”