Manager Sean O'Driscoll is not concerned that many of Nottingham Forest's players are coming to the end of their current contracts at the club.
Seven City Ground squad members will see their current deals expire in the summer.
O'Driscoll admits he is keen to open talks with players but insists that the situation at Forest is not uncommon.
He said: "The way football is going no-one gets long contracts so each year you have five or six coming out of contract.
"It is a situation we are aware of and want to resolve as quickly as possible."
Tuesday's penultimate Group G encounter will take place at the Stadium of Light but Lennon will take his players to the Estadio Nacional to train in the morning, the scene of the club's famous European Cup final win over Inter Milan in 1967.
Several of the Lions were on the official flight today where they were joined by the trophy, which took up two seats at the back of the plane.
A win for Celtic will guarantee them a place in the last 16 with a score draw being enough if Barcelona beat Spartak Moscow, and Lennon is looking for every advantage.
He said: "1967 is a pivotal day in our history and we all aspire to reach those heights again.
"The Lisbon Lions are a very special team, a unique bunch of men in the history of the club, and it is very poignant that we are playing in Lisbon.
"We will train at the stadium in the morning and let these current players get a feel of what is a special piece of history for our club.
"We did it (trained there) in 2007 and it might inspire them to play as well as they can."
