Steve McClaren said scoring the first goal was crucial in Saturday's huge game at the Riverside.
George Boateng grabbed that goal for the home side and it was enough to take maximum points and leave Boro needing a point from their final fixture at Manchester City next week to book a place in Europe.
"I was getting a bit frustrated in the second half because we had that many opportunities on the break, and with a bit more care and better finishing, we would not have been so nervous at 1-0 going into the last 10 minutes," said McClaren.
"It was essential to score first, essential to score early. It settled everybody down and we settled then into the game-plan that we had, which was obviously to sit behind the ball and hit them on the break, and we should have won by more."
Both ourselves and City could also make it into seventh on what will be a nerve wracking final day.
"Somebody said yesterday at the press conference 'is this the biggest game of the season?' and it was, and I said 'hopefully there'll be another one', and now there is," said McClaren.
"It's like a cup final, a play-off game, but today we used the experience that we have got in the team to cope with the occasion, to cope with the pressure, and to give a performance like that stands us in great stead for next week.
"They (City) are on a good run, but our destiny is in our own hands. Anybody who has seen us play over the last seven or eight games can see the determination among everybody to get the job done."