Liverpool took control with four goals in the opening 51 minutes. Barcola scored twice, while Ronald Araujo and Jeremie Frimpong also found the net with headers.

Robert Ljubicic pulled one back for LASK before Barcola completed his hat-trick. Koumas then added a sixth goal for Liverpool, while substitute Florian Flecker scored twice for the hosts.

Iraola was particularly pleased with the performances of Barcola and Florian Wirtz, who helped Liverpool break down a compact LASK defence.

"Bradley, apart from the hat-trick, was always a threat, one-v-one and threatening in behind," Iraola said.

"Flo helped us a lot to control the game, finding the pockets. I'm happy for both of them."

The Liverpool coach believes the goals could provide an important confidence boost for both players.

"I think their confidence, for sure, is very good. I think they feel that we trust them a lot," he added. "To enjoy a little bit playing in the Champions League away, I think it's going to be very good for them."

Iraola also highlighted Liverpool's ability to find space against a LASK side that defended with five at the back.

"Against a very compact block, it's not easy. They play a back five and there's not a lot of space in between," he said.

"I think we found very good spaces in the pockets, spaces in behind with the three players up front. Offensively, it has been a very complete game."

Koumas and fellow youngster Trey Nyoni were among the players to benefit from Liverpool's rotation, with both earning their first Champions League starts.

Iraola stressed that the young players were trusted members of the first-team squad rather than simply academy prospects being given an opportunity.

"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 coach was especially pleased to see Koumas score after having two previous efforts ruled out.

"I was really pleased for him to score a goal and celebrate with the supporters, enjoy a little bit your first Champions League goal," Iraola said.

He believes performances like these will help Liverpool manage the demands of a congested fixture schedule while giving more experienced players valuable rest.

Despite the emphatic victory, Liverpool conceded three goals, with Iraola acknowledging that changing both centre-backs at the same time was a difficult decision.

With another match approaching quickly, he wanted to protect players who had accumulated significant minutes for club and country.

"When you're winning 4-0, I have to start thinking about the next game," Iraola said, pointing to Liverpool's upcoming Premier League trip to Brentford.

He admitted that replacing both central defenders was not ideal, but felt the decision was necessary given the workload facing his squad.

Liverpool will then return to Champions League action against Villarreal, leaving little time for recovery between matches.

Iraola believes the contributions of younger players such as Koumas and Nyoni will be crucial over the coming weeks.

"We will need more than 11, more than 12, more than 13," he said.

Liverpool's next challenge is Saturday's Premier League meeting with Brentford, where Iraola will hope his side can carry their attacking confidence into another demanding fixture.

Sjovold fires Bodo/Glimt to stunning victory vs Dortmund in Champions League