Liverpool took control before half-time through Ronald Araújo’s header and two finishes from Barcola, who opened his account for the club after a difficult start. Jeremie Frimpong headed in Kostas Tsimikas’ cross six minutes after the break to make it 4-0.
Robert Ljubičić pulled one back for LASK, but Barcola completed his treble after meeting Frimpong’s delivery. Koumas then scored Liverpool’s sixth, before Florian Flecker struck twice late on for the hosts.
“I think we attacked really well, especially first half,” Iraola said. “Against a very compact block it’s not easy. They play a back five and there’s not a lot of spaces in between. I think we found very good spaces in the pockets, spaces in behind with the three players up front.
> “Obviously the second half probably was more about exploiting the spaces. But I think offensively it has been a very complete game.”
Barcola’s three goals were especially welcome after scrutiny of his quiet start at Liverpool. Iraola was pleased with the Frenchman and Florian Wirtz, who helped create chances and control the match.
“I’m really happy for Bradley because you were asking me yesterday about him not making the numbers, also Florian. I think both of them today played really, really well. I think they made a difference,” the manager said.
“Bradley apart from the hat-trick, I think he was a threat always – one-v-one, threatening in behind. Also Flo helped us a lot to control the game, finding the pockets. I’m happy for both of them.”
Iraola also praised Koumas and fellow young midfielder Trey Nyoni, who both made their first Champions League starts.
“They are first-team players for us. They are first-team players because we trust them and we think they can give us the level to help during the season,” he said.
The manager was particularly pleased that Koumas scored after having two earlier efforts ruled out for offside.
“I was really pleased for him to score a goal and celebrate with the supporters, enjoy a little bit your first Champions League goal.”
Liverpool’s defensive display, however, became less convincing after Iraola replaced both centre-backs with the match apparently under control. He admitted the decision to change the pairing had contributed to the difficulty of managing the closing stages.
“I think there is a reason why managers would never change both centre-backs together. Because it’s difficult to change both centre-backs, a new pair comes in straight away,” he said.
With Brentford and Villarreal approaching in a demanding schedule, Iraola said Liverpool would need contributions beyond the starting eleven. The win provided confidence, but the three goals conceded offered a reminder that the performance was not without flaws.