Raul Asencio was sent off only on seven minutes for hauling down Salomon Rondon when through on goal. However, Real shook off the setback to go to a 3-0 lead through Fede Valverde, Jude Bellingham and Arda Guler before Elias Montiel scored a late consolation.
Afterwards, Xabi said: "I'm not going to say that the three goals came because we worked on the midfielders' runs, but we did talk about it during the water break. They have the quality and their finishing was fantastic. It gave us an advantage in a difficult situation, as we were down to ten men from the seventh minute.
"The team showed discipline and sacrifice, knowing how to control the game without the ball. We knew that if we recovered it, we could get out and that's how the goals came. Going 3-0 up was important so that we didn't have to push too hard if we conceded, as happened afterwards. It's a victory that strengthens us a lot in terms of our football and our morale to compete in this tournament."
Happy with defensive actions
Xabi also said, "We had to defend with a player fewer in a low block and you have to know how to suffer and have the humility to find the right moment. The defensive line held the area well and we had good periods of possession.
"We took a lot of positives from the game, especially the three points. We weren't able to show what we've been working on. We had to adapt to the game by staying balanced and maintaining possession so that the players felt comfortable."
On Valverde, he added: "I haven't seen many players with his physical ability. He reminds me of Steven Gerrard. He can play anywhere and I'm very happy to be coaching him. Every coach would like to have a Valverde in their team. He made up for the penalty the other day and showed his fighting spirit in the celebration."