'Alberto Moreno is 100 percent back, which is very nice after a really hard year.
The Reds boss watched 19-year-old summer signing Dominic Solanke score again, along with 17-year-old Ben Woodburn, while Alberto Moreno impressed at full back.
The Merseyside out have addressed their weakness at left-back with the £8m addition of Scotland global Andy Robertson from Hull City.
Striker Firmino was sharp, winning and converting a penalty to open the scoring on 21 minutes despite established penalty-taker James Milner also being on the pitch.
New signing Mohamed Salah was involved in most Liverpool attacks and tried a shot towards the far corner from a challenging angle while his trickery helped to confuse Atheltic's defence.
But it wasn't all smooth sailing against the La Liga outfit and Klopp was visibly (or should we say audibly) frustrated at stages. Ryan Kent, I've known him for one-and-a-half years and last year he developed unbelievably well and this pre-season is completely different to last pre-season, he's completely showed up now. Dom Solanke, he already showed that he is ready for some adult football. Without too much money for these players, because they were pretty much already ours, we have additions in the squad so that's good'.
The Welsh underage global scored the side's second goal.
On front of a passionate support of Irish fans, Jurgen Klopp played a strong team despite the absences of Adam Lallana, Philippe Coutinho, Daniel Sturridge and Jordan Henderson. Phil had a back problem yesterday, so there was no reason for any risk.