The Scottish champions put themselves in control of their own destiny in their bid to qualify for the last 16 by beating the Catalans 2-1 at Parkhead 10 days ago.
The shock win followed their impressive defensive display in the Nou Camp when they were seconds away from taking a point before Jordi Alba grabbed a winner.
The games have captured the imagination of Celtic fans young and old but Lennon stressed their whole Champions League campaign has thrilled him.
And he believes Tuesday night's fixture in Lisbon against Benfica, when a draw could be enough to send Celtic through with a match to spare, will be every bit as difficult as their game in Barcelona.
Lennon said: "I really enjoyed the first game against Benfica and qualifying against Helsingborgs was a tremendous night for the players and the supporters. The win in Moscow was a huge psychological lift and it broke the hoodoo.
"Benfica away is as difficult as Barcelona away. Spartak at home will be very dangerous because they might just come here with nothing to lose."
Celtic drew 0-0 at home to Benfica in a tight opening fixture which was the debut Champions League group game for the vast majority of their team.
But they have grown in confidence since then with a 3-2 win over Spartak showing they could take the game to teams away from home, before they defied the odds with their performances against Barcelona.
Lennon said: "So far the players have given us a hell of a ride. I don't think anyone would have expected us to be where we are now.
"We have given ourselves a good foothold in the group and the players are developing very well.
"The expectation after the Barcelona game is that 'you are going through to the last 16, it's going to be comfortable for you'.
"But we still have a lot to do."