The Scottish champions were beaten 2-0 by Kazakhstan outfit Shakhter Karagandy as the minnows took control of the play-off tie, but the Bhoys' boss has backed his side to respond
The Scottish champions were made to pay for some poor defending and wasteful finishing in the final third, as goals from Andrey Finonchenko and Sergei Khizhnichenko gave the hosts a healthy advantage at the Astana Arena.
The result leaves Celtic facing a difficult challenge to reach this season's group stages, but Lennon believes that they can still turn the tie around in the return leg at Celtic Park on August 28.
"It's a big task but the tie is far from over," he said. "We have plenty in us to turn the deficit around.
"The players will be very motivated. A few of the players are disappointed with their performances.
"We're still well in this tie but there's a lot to do."
Lennon admitted that his side's lack of cutting edge had proved particularly costly, but believes there are positives to take ahead of the second leg.
"We lacked a bit of composure in the final bit, we just needed a goal to change the complexion of the tie," he added.
"[But] we had plenty of chances and it gives us plenty of encouragement for the second game in Glasgow."