Middlesbrough manager Aitor Karanka claims Arsenal boss Arsene Wenger showed respect to his side by naming his best starting line-up in the Gunners victory on Sunday.
After Middlesbrough beat Manchester City in the fourth round, Wenger took no chances and named a strong XI including Santi Cazorla, Mesut Ozil, Olivier Giroud and Alexis Sanchez, despite concerns over the Chilean's fitness ahead of the match.
The FA Cup holders beat Karanka's side 2-0 to reach the quarter-finals thanks to Olivier Giroud's first-half brace.
Karanka was left frustrated with the first-half performance but pleased with the respect shown by Arsenal.
"Their selection was the best thing. Man City played their best team and so did Arsenal which means they respected us," the Spanish manager told a post-match press conference.
"It was difficult, especially in the first half. We didn't play with the intensity that we can and when you're not at your best against a team like Arsenal it's difficult.
"I was disappointed with the first half. I wanted us to fight in the way we did against Man City and Liverpool but we didn't in the way I would like."
Karanka however believes his side improved during the second half, adding the defeat will help them to focus on their battle to secure promotion to the Premier League.
"It's difficult not to concede goals against Arsenal and if you make mistakes at set pieces it makes it harder," he said.
"The first half was key, we went 2-0 down at half time and playing in the way we did made it very difficult but we played better in the second half.
"Now we think about Birmingham and the league is our main objective."