The 22-year old Colombian blasted a 30-yard strike into the back of the net in just the sixth minute before New England's Shalrie Joseph netted a double to take the points away from the Sounders.
Despite the loss, Montero was happy with his brilliant goal.
"It was different feeling because it was a long shot - a long distance - and I was not expecting it to go in," he said through a team interpreter.
"But it was amazing the way the ball kind of curled in the air and it went in."
Sounders coach Sigi Schmid said Montero's goal would be a contender for goal of the season.
"It was a great goal. It was a wonderful strike and probably goal of the week - and should be one of the goals considered for goal of the season. But it was a great strike," Schmid said.