Arsenal eased to a 5-1 aggregate victory despite their 1-1 home draw, proving too strong for Slavia Prague with three goals inside the opening 25 minutes.
The goals came in a burst too, after Emile Smith Rowe had a goal disallowed, before Nicolas Pepe (18’), Alexandre Lacazette (21’) and Bukayo Saka (24’) all struck to settle the tie.
“I think the reaction. When Emile scored the goal and it was disallowed, the team straight away reacted and wanted more,” Arteta said.
“Again, we were brave, we were really efficient in a hard place, we put them under a lot of pressure and then when we had to make a decision with the ball in the final third, we were really clinical.”
The result means the Gunners will meet Spanish club Villarreal in the final four. Villarreal are managed by ex-Arsenal boss Unai Emery who has won the Europa League times with Sevilla.
“It will be a tough game,” Arteta said. “Villarreal are a tough side and Unai Emery is the most successful manager in this competition.
“We’re going to enjoy tonight and we know we’re going to have time to prepare for that one. There’s no time to prepare for Fulham on Sunday but this is where we are.”
Meanwhile, Manchester United eased into the semi-finals with a 2-0 triumph over Granada completing a 4-0 aggregate win.
The Red Devils will play AS Roma in the final four after they edged past Ajax Amsterdam 3-2 on aggregate despite a major second-half scare.