Brown was forced to miss in Celtic's 1-0 win in their Scottish Premier League opener due to a hip injury.
Lennon has said that he will need to monitor Brown very closely before deciding if the Hoops captain is fit to travel to Finland.
He told Sky Sports News: "Scott had a scan on his hip and he has a bit of degeneration in there, on the disc. It might mean an injection and hopefully that will calm it down.
"It is never a risk when you play Scott but we will work closely with him over the next couple of days and see how he is."
Brown's presence in midfield will be crucial for Celtic as they bid to hold on to a narrow 2-1 advantage to keep alive their hopes of qualifying for the Champions League Group Stage.