Academy graduate Lallana has not featured for Saints since re-joining the club but he has become an important figure behind the scenes.
Martin spoke to the Daily Echo about the role he plays amongst the squad.
"He's been brilliant. To be on the pitch was not the only reason we signed Adam. I said that at the time. He's going to really drive things for us with the players in that group and be a voice.
"He is already (a voice) in the meetings, which is brilliant. It's enabling the others to grow a little bit and lead a bit. Taylor, Flynn, Jack, all those guys.
"He's been brilliant for the group. He's back on the grass now and, hopefully, he'll be involved in the next week or two, but he's not just a player for us.
"It's about everything that he brings in terms of leadership and football intelligence and belief in the style of play that we have and understanding the club.”
Lallana is an inspiration to the youngster members of the squad and Martin thinks he is one of the most important members of the squad.
"He knows what the young guys have been through because he's been there. It's going to be hugely important for us. He'll be a really, really important signing.
"Hopefully for moments on the pitch as well, but mostly for everything else around that and what he brings."