The Portuguese manager added that his side were not worse than Boro over the course of 90 minutes in the third-round tie and were unlucky to end up on the wrong side of the scoreline.
He said: "We played our game, we moved the ball, we controlled the game. I am happy with my players and the way we played against a Premier League team.
"I am unhappy with the score, of course, but circumstances made us lose this game. We lose together and we win together. We don't put any responsibility on any player because it's a team work and circumstances of the game that everybody saw made us lose this game.
"It was not because we didn't try, we didn't put in our energy, we didn't play our football. The first and second goals, it was strange the way we conceded the goals and of course that makes a difference.