Having made it through the group stages of the competition, the Bhoys suffered a 3-0 defeat in the first leg of the last 16 clash with Juventus on Tuesday.
The Scot has no doubts that his side are going to need drastic fortune if they are to turn the tie around.
"We need a miracle," Lennon told ITV. "But it's the harsh reality of Champions League football and some of my young players will learn a huge lesson tonight.
"Efe was poor for the first goal but we had good chances to equalise. Then we switched off defensively for the second goal and the third goal was poor.
"I thought for 70-odd minutes, until the second goal, we were by far the better side - but you can't give away goals like we gave away, we were sloppy."
The Hoops travel to Italy for the return leg on March 6.