Antoine Griezmann struck early as Atletico won 1-0 - marking 13 consecutive wins for the team.
Vivas later said: "With total calm, with humility. Focusing on the things we can do better in each game. That's how we approach the first day of the week before each game.
"What usually happens in these competitions... when you don't close things out quickly, you don't finish them off. The boys are aware that they could have been better in terms of forcefulness and precision. The match was controlled, but with a small margin until the end."
He added, "The fact that we played on natural grass, with the dimensions we are used to and against an opponent who gave us comfortable time to decide... we did feel that the game was easy, but not because of the result.
"In general terms, we created chances. There could have been more, but we are satisfied and happy with the victories and with this qualification and continuing in the competition. There are others who have eliminated teams of a higher category."