The visitors won the game 3-1 with goals from Rade Krunic, Brahim Diaz and Jens Petter Hauge. The latter made sure of the points after Mohamed Elyounoussi had reduced the 2-0 first-half deficit with a 76th minute header.
Coming off the back of Saturday’s dismally poor performance in the defeat to Rangers, Lennon’s side endured another lacklustre half as they fell behind to the Italian visitors. But a change of formation and a couple of substitutions, particularly the introduction of Tom Rogic, dramatically improved the performance after the break.
The Celtic boss told BT Sport: “We deserved better from the game. There wasn’t much in the first half – we conceded two soft goals from our point of view – second half we were terrific. The third goal is academic. It comes from us chasing the game.
"I thought we started the game brightly, could have taken a couple of half-chances better, then in the second half we got into some really good areas but our final ball needs to be better at this level.
"The response and the reaction from the disappointing defeat on Saturday was a lot better. Our body language and energy were so much better. I’m still not happy about losing the game and losing at home, but there’s a lot to be encouraged about with us getting players back and up to speed.
"We couldn’t start with the 4-3-3. We didn’t have the wingers as Ryan wasn’t fit enough to start the game.”