Academy graduates Emile Smith Rowe and Bukayo Saka both starred for the Gunners as they shocked the hosts with a fine first-half display, hitting three goals in six minutes en route to a 4-0 win on the night.
Smith Rowe had a goal ruled out by VAR for offside before Nicolas Pepe opened the scoring, Alexandre Lacazette then converting a penalty after Saka was fouled before the England international added the third himself.
Lacazette would strike again in a more timid second half to see Arsenal through 5-1 on aggregate and into a last-four clash with former head coach Unai Emery and his Villarreal side.
It was Emery who gave both Smith Rowe and Saka their senior debuts for Arsenal during his 18-month reign at the club as Arsene Wenger’s successor.
The pair have now gone on to become important parts of Arteta’s squad and the Spaniard was delighted with their performances.
“For me it is a joy to watch them play, to watch them every day in training,” Arteta said when asked about the performances of Saka and Smith Rowe. “How they behave, the passion and the commitment they have for the club. And then how much they like to play football.
“You have to let them express themselves, and give them certain frameworks to work in and some ideas on how they can exploit their qualities. Then it is up to them and I thought both of them were really good today. Credit to (all) the players, for how they approached the game and how brave they were in their approach.
“We were brave, we were efficient, we put them under a lot of pressure. And in the final third we were really clinical. We know how important the competition is.”
After wasting a hatful of good chances in the first leg, Arteta called for his side to be more clinical.
They dispatched Sheffield United in the Premier League on Sunday with a comfortable 3-0 win and, with Smith Rowe in for Gabriel Martinelli in the only change, they held that same lead in Prague with less than 25 minutes on the clock.
Both results came without captain Pierre-Emerick Aubameyang, who revealed on Instagram before the game that he contracted malaria while on international duty with Gabon last month.
Asked about his absent skipper, Arteta replied: “We just spoke with him. He’s at home, he’s fine. He had two days in hospital to get the right treatment, but he’s feeling good now.
“We will see how he recovers. I think he will need a few days to recover from that, but he wants to be back as soon as possible. That’s what he said to me.
“When he wasn’t involved against Sheffield, two days before he wasn’t feeling good, but nobody could expect that was the case.
“They did some more tests and that’s when it came up and straight away the doctor realised very quickly what had to be done and they did a great job. He’s safe and he’s feeling good.”
With Aubameyang missing, Lacazette took the focal role as the central striker and his brace saw him move onto seven goals in his past nine games. Wearing the armband, the France striker also made an impact before kick-off, taking the knee in front of the entire Slavia line-up in a stand against racism.
Slavia were without Ondrej Kudela, the defender hit with a 10-game Uefa ban on the eve of the match having been found guilty of racially abusing Rangers midfielder Glen Kamara in their round of 16 clash. Asked about the gesture, Arteta explained that his players had requested permission to make a stand.
“They asked me and the club that they wanted to take that initiative,” he added. “They had the right reasons for it, so the club was very supportive. I was supportive and thankfully the referee, and Uefa, they’ve been supportive. So I think it was a good gesture.
“They came to me, they wanted to take that initiative. We spoke with the club to make sure that we could follow the rules of Uefa and we can do it in the right way. We decided to take that approach, which I really like from the players, and I must say that Uefa was very supportive as well. The captains came to me and asked me to do that, and I just supported them like the club did.”