Kris Commons volleyed the Scottish side into the lead with less than two minutes on the clock following a cross from Georgios Samaras. Hoops goalkeeper Fraser Forster made a series of saves as the Swedish champions fought back but in the 75th minute Samaras put Celtic in the driving seat for next week's second leg in Glasgow when he headed in a Commons corner.
However, Lennon said afterwards: "There is still a lot to play for in the tie as far as I am concerned. I don't think it's over although our home record is very, very good."
He added: "There was enough there to worry me as Helsingborg were very impressive. But in the end we hit the bar twice and, on the counter-attack, we could have put the tie well out of sight.
"We'll set the team up differently and I'd like to think we would be in the ascendancy in the home game.
"It's a great result for us to take into the second game. A clean sheet and two away goals was more than I could have asked for really."
Lennon rated the result as one of the best in his managerial career.
He said: "It's one of them. It's up there. But there is still a lot of work to do and 90 minutes still to go. There are a few bumps and bruises in there so we might have a casualty count in the morning.
"It's been a really hectic schedule for the players so their efforts tonight are even more remarkable. They are pretty grounded boys and they know they still have a big night ahead of them.
"But there's a big prize at the end it for them and you can see what it means for them. We might have to weather a bit of a storm at times in the second leg but I'm certain we will have more possession in the home leg than we did tonight."
- Kris Commons
- Fraser Forster