If what he concedes is the necessity to sell is not to be repeated this time next year, then his team must defeat Helsingborgs IF and qualify for the group stages of the Champions League, which would guarantee a £12m boost to their income and he admits: "Help fund the club's debt and get it down a little bit".
Eliminating the Swedish champions over the two legs, which begin here tonight and conclude a week tomorrow at Parkhead, could afford Lennon the opportunity to supplement his squad as it would mean that, combined with the sale of Ki, around £18m would drop into the club's coffers.
The manager has already identified potential signings, but insisted it is no given they will actively pursue them as he might elect to give the players he already has the chance to prove themselves on the club game's biggest stage. As Ki inches closer to the exit, Lennon concedes developing young talent and selling for a profit is an essential part of the club's business plan.
Swansea may yet face stiff competition for the 23 year-old South Korean, enhancing even further the profit Celtic have made on their £2.1m investment. QPR and Fulham have made their interest official, and other clubs may also now be smoked out.
Lennon admitted: "We were always going to have to sell one of our players. You just have to be pragmatic about it. It's good business sense, and, if selling a player keeps everything ticking along nicely for us, then so be it.
"That's where we are at the minute. We develop younger players and eventually sell them on. But we are no different from some of the top clubs. Just look at Arsenal selling Robin Van Persie. They didn't want to sell him, but it was a necessity for them in the end.
"Ki will be a loss, but I think it's a loss we can adapt to. This is a good time for him to move, and a good time for us. He only has 15 months left on his contract and we think it's a good offer."
Lennon has always been prepared to sacrifice one player to ensure he could retain the rest, but, in this respect, Champions League participation would be a game changer in the future. "There is a nice pot of money there that will keep the club stable for quite a while," he said. "Maybe we won't have to break the squad up. By that, I mean maybe selling one player. Maybe we can enhance the squad as well."
Should Celtic get past Helsingborgs, improving players' existing salaries may, however, be a more practical way of utilising extra income.