Mane, who Liverpool signed in a £34million move from Southampton this summer, impressed as the Reds beat Barcelona 4-0 at Wembley on Saturday.
And England international Lallana, who created the new signing’s opener, expressed his excitement at the 24-year-old’s potential.
“I knew straight away what he was about. I knew what he was going to bring to the team, regardless of what everyone has seen in pre-season,” he said.
“You saw all those different parts against Barcelona but I saw them all in his first couple of sessions with us.
“We have seen it from working with him what he can do. I was never worried about him settling. He could have had a goal against AC Milan but it didn’t matter.
“I could see what he was going to bring to this team. He is different to what we have got. He is unpredictable.”