However, Benfica attacked after the break and forced a nervy ending when Javi Garcia nodded home five minutes from time.
"As I said yesterday in the press conference, we expected a difficult game, a hard game, and that proved to be it exactly," he said.
"We probably made it a little bit more difficult for ourselves by not scoring a second goal, especially in that second half with all those chances. That kept them alive and [gave them] hope that they would score a goal and still be in it.
"They moved the ball around very nicely. We didn't quite keep possession enough as we'd have liked to with the extra man.
"I think the team wasn't as sparkling as we were hoping it would be. Maybe they were a bit tired, but we're pleased to have won the game and gone through. We deserved it over the two legs."