Manager Arsene Wenger says Arsenal were always in control in the 2-0 win against Middlesbrough on Sunday.
Middlesbrough, who eliminated Manchester City in the previous round, had no answers to Arsenal's pacey attacks in the first half and could only admire as the Gunners eased to a 2-0 lead through an Olivier Giroud brace.
And the Frenchman's goals were enough for Wenger's side as they reach the quarter-finals of the competition.
"We controlled the game from the first to the last minute," Wenger said.
"They had one chance at the end from a header, but overall I'm pleased with the way we attacked, the way we defended and with the way we played together with a good focus for 90 minutes. That's basically it.
"They [Middlesbrough] are a good side, well organised and if they had come back to 2-1 I think we would have struggled a little bit.
"They played good football with a good fluency in their game. We managed not to give them any chance today but overall you feel it is a good team.
"We have a week now to prepare for the Crystal Palace game and I did rotate today as well.
"I changed two defenders from our last game. It shows that everybody's focused and has the quality to compete for places in the team. At the moment, in every single position, we have two very good players."
Defender Gabriel Paulista made his long-awaited debut since joining from Villareal and Wenger was happy with the performance of the 24-year-old.
"It was interesting to observe Gabriel today because he played his first game in a cup game that we absolutely had to win," the Frenchman said.
"He has shown three important qualities - great concentration levels, great urgency to defend and good pace, especially on the recovery tackle he made in the box.
"On the other hand, he played a little bit with the handbrake on because he did not want to make a mistake. From what I've seen there's a lot to come from him because technically he is good at passing as well."
