The result means that the Bhoys sit second in Group G with two games remaining and Lennon believes that there is more to come from his team ahead of the final two fixtures.
"It's one of my proudest nights of my career. It's a monumental effort from all those players," said Lennon.
"My players have just beaten the best side in the world. But there's more to come from us."
Benfica beat Spartak Moscow 2-0 in the other fixture in the group.