The Hoops had to fight their way through two qualifying rounds and were then unfancied when drawn alongside the Russian club, Benfica and Barcelona. However, with seven points from five games, including a famous 2-1 home win over the Catalan giants, the Scottish champions will go through to the last 16 if they get a better result against bottom-placed Spartak than Benfica get in the Nou Camp.
The former Celtic skipper, who became boss of the Parkhead club in 2010, said: "It would be my best achievement as a manager here."
Lennon added: "It would be great for everyone associated with the club and it would give the players something to look forward to and get their teeth into in the new year. No one gave us a prayer coming into the competition.
"There were people saying we wouldn't get a point and people saying we wouldn't get into the Europa League but we felt that we had a decent chance and that's what we have given ourselves.
"However, regardless of the outcome, we will have European football (in the new year) and that was one of the targets going into the group. Which competition it is in remains to be seen but we would all love to be in the Champions League, obviously."
Celtic's task may have become more difficult with the news that Barcelona are set to leave out Javier Mascherano, Jordi Alba, Xavi Hernandez, Cesc Fabregas, Andres Iniesta and Pedro Rodriguez for the visit of the Portuguese club.
However, Lennon said: "I am not concerned with what other teams are doing in the competition.
"I am concerned with my own team and how they play tomorrow evening, and regardless of whether Barcelona leave six players out, the six players who come in will be quality.
"What I want is for us to win the game and that would mean Benfica would have to win in Barcelona."
Source: PA
Source: PA