Spurned chances and moments of uncertain defending were a reminder of the flaws the manager is hoping to eradicate with his new players.
This game ought to have been a cause for self-congratulation, since Celtic created a slew of goalscoring opportunities, but it delivered only regret.
Solutions are at least close to hand. Efe Ambrose, the Nigerian centre-back, and Nicolas Fedor, the Venezuelan striker, were introduced to the crowd before kick-off. Afterwards, Lennon also revealed a deal has all but been completed with Lassad Nouioui, a 6ft 2in Tunisian striker who is a free agent after a three-year spell at Deportivo La Coruna.
"We've agreed terms and the paperwork is done," the manager said. "He leads the line very well. We missed chance after chance and could count ourselves very unlucky not to win the game."
Domestic fixtures suddenly present a challenge to Lennon. The Champions League is a prestigious source of clutter, since the demands of the midweek games place an additional strain on the squad. Celtic's mood following the play-off victory over Helsignborgs last Wednesday night was buoyant, but there are always practicalities to address.
Four players were brought into the starting line-up, but disruption was initially kept to a minimum. The team acted as though the effect of the changes could be disregarded. There was a swashbuckling air to the home side, although the opening goal itself was a mundane affair. Mikael Lustig met Filip Twardzik's corner with a crisp finish, but Hibernian should have defended the set-piece better.
Spirits were raised, and Celtic performed as though convinced of their superiority. There was even a spell of virtuosity. Gary Hooper's astute pass allowed Victor Wanyama to shoot and his effort was saved by Ben Williams. The ball spun out to James Forrest, who pirouetted over it to shake off two defenders. His shot was blocked, but the ball then ran to Paddy McCourt, who jinked past three players before passing to Tony Watt, who fired over.
Hibs might have been reeling if their minds weren't preoccupied with their own failings. The defending was hesitant, and Hooper hit the crossbar with one shot and struck a post with a header. Celtic's dominance was so well established that it appeared infallible. The indiscretions had merely been kept out of sight, however. Hibs were more dynamic in the second half, pressing higher up the pitch and moving the ball forward quicker. The effect addled the home side.
When Eoin Doyle sent the ball into the penalty area, Lustig was marshalling it back towards goal, but waited for Fraser Forster to come out to clear it. In the meantime, Tim Clancy stole in and stabbed a shot into the net.
The error was conspicuous, but it could not deflect from the significant difference in Celtic's performance after the interval. Even with a dead leg, Wanyama had been a powerful and domineering presence in the middle, and his absence , having been substituted, hampered Celtic. Twardzik is an elegant and clever passer of the ball, but he and Jackson Irvine, Wanyama's replacement, could not take control of the midfield.
Individuals could still be eye-catchingly effective, and another typical McCourt slalom run took him past three Hibs players. Yet it was also customary for him to shoot wide from just inside the penalty area. Hibs were generous, too, though, and Williams spilled a long-range free-kick from Twardzik. The ball fell to Lustig, and his shot was diverted over the line by James McPake.
The reprieve should have allowed Celtic to regather their composure, but the carelessness could not be discarded. Adam Matthews was lax in allowing Paul Cairney to dribble past him before the young Hibs midfielder curled a shot beyond Forster. "We missed two tackles, and you can't do that at any level," Lennon said. "It was poor from players who have been superb."
The scoreline reflected Celtic's lapses and a new-found resolve in the visitors. "We gave away too many chances, but in the second half I thought we played really well," said Hibs manager Pat Fenlon. "It's a different type of character we have in the dressing room now, they want to scrap for each other."