With a long injury list and one eye on Wednesday’s crucial Champions League qualifier, Lennon fielded a makeshift Celtic side at the Caledonian Stadium with teenagers Tony Watt and Filip Twardzik handed their first starts as the Hoops made six changes.
Watt, who scored a double on his debut as a substitute against Motherwell last season, impressed with goals in either half to grab a double on his first competitive start.
Victor Wanyama had headed Celtic into third minute lead before Watt doubled the advantage in the 25th minute when he clipped the ball over keeper Ryan Esson.
Captain Charlie Mulgrew made it 3-0 in the 48th minute with a neat finish from a well-worked free-kick before Watt got his double with a rifled shot in the 64th minute.
Inverness rallied in the final ten minutes of the match with Ross Draper grabbing a double but it was little more than consolation for the hosts.
The Hoops now take on Swedish champions Helsingborgs at Parkhead on Wednesday as they bid to make the group stages of the Champions League for the first time since 2008.
Celtic hold a 2-0 advantage from the first leg and Lennon says the performance of his fringe players has given him some food for thought going into the game.
“The squad is taking good shape now. I thought Watt had a sensational game and Twardzik was excellent as well,” the Celtic manager said.
“They’ve done themselves no harm at all with that performance. The senior boys all contributed brilliantly as well.
“Watt was sensational. We threw the gauntlet down to him before the game and he responded brilliantly.
“He has got some very good assets and if he keeps going the way he is going we think we will have a great player on our hands. He’s full of running and was a real handful for the back two all day.
“It is not an easy place to come and he just gives us something a little bit different.
“He was full of running and power and they were two great goals as well.
“Twardzik we have known about for some time now and it was just a case of giving him the opportunity to get in and he was very good.
“That will have done some of them a world of good. Paddy McCourt got a great 90 minutes as did Mikel Lustig so the squad is taking a bit of a shape now.
“Considering the hectic schedule that we’ve had they’ve performed very well.
“They have done very well in a very difficult tie and it was a great performance and result.”
Lennon was without several first team players as they struggled with minor knocks but the Hoops boss was confident of welcoming some back for the vital Champions League tie.
“Wednesday is such a huge game in the context of our season but hopefully the players who played in the first leg, the likes of Kris Commons, Georgios Samaras, Scott Brown and Thomas Rogne, will all play,” Lennon said.
“But Beram Kayal and Joe Ledley are definitely out.
“My only focus is just about Wednesday night now. For this young team to progress and enhance themselves then Wednesday is important to them and if we can get through the tie you never know where it will take them.”