Arsene Wenger said he was "proud" of the clinical display that saw Arsenal beat Celta Vigo 2-0 and secure a place in the Champions League quarter-finals.
"We controlled the game. The way that we handled the game shows we have matured," he told BBC Sport.
"The fact we didn't concede a goal once we were 2-0 up was very professional.
"Psychologically we did the biggest part of the job at Celta Vigo. To score three away goals had a deep effect on their belief," added the Arsenal boss.
"It was important to start the game by scoring goals and then not to put ourselves in trouble by being steady defensively and we did that."