A much-changed Celtic suffered the first defeat of their Europa League campaign as second-half goals secured a 2-0 win for CFR Cluj in northwestern Romania
Andrei Burca rose to head the hosts in front three minutes after the restart before Damjan Djokovic stabbed home a second with 20 minutes remaining as Cluj qualified for the knockout stages of a European competition for the first time in their history
Dan Petrescu's side secured second place in Group E while Celtic were denied a maiden unbeaten European group-stage campaign
The visitors finish the group on top with 13 points, one ahead of second-placed Cluj and attention will now turn to the draw for the last 32 on Monday in Nyon, with Celtic among the seeded teams
Lennon said following the defeat: "Overall, we've had an amazing campaign and I'm happy to have used the squad tonight because we have so many important domestic games coming up
"The Celtic boss was also happy with the performance of 18-year-old Scott Robertson on his senior debut, while at 16 years and 293 days old, Karamoko Dembele became the youngest player to ever play for Celtic in major European competition
The Scottish champions were already assured of their place in the last 32, and this was remarkably the fourth time these two sides have met this season, first meeting at the Dr
 Constantin Radulescu Stadium on August 7 in the Champions League qualifiers - but Giedrius Arlauskis, the Cluj goalkeeper, was rarely troubled
Despite having already sealed top spot, 1,000 Celtic supporters made the trip to Transylvania hoping to witness the club's first win in Romania, but it was the hosts - with the extra incentive of needing a point to secure second spot - who created the best openings of a cagey first half
Lacina Traore, the giant Ivory Coast striker once on loan at Everton, led the line well and set up Billel Omrani with a cute reverse pass after 18 minutes but Craig Gordon raced from his line to smother the shot
Celtic's best efforts came from distance, as after Nir Bitton's speculative drive was comfortably kept out by Arlauskis, Mikey Johnston came within a yard of finding the top corner when his dipping shot from outside of the box deflected just wide
But Cluj emerged from the second period with greater urgency and duly broke the deadlock when Burca lost his marker Boli Bolingoli to head home Ciprian Deac's corner
Gordon appeared to still be reflecting on that incident when a sloppy pass out from the back presented the ball straight to Deac, but the stand-in Celtic goalkeeper made amends with a fine one-handed save around the post to ensure Cluj didn't celebrate a quickfire second
Celtic showed resilience earlier in the group campaign, coming back from a losing position away to Rennes, and both home and away to Lazio, but after Leigh Griffiths and Mikey Johnston spurned half chances either side of the hour, Cluj pulled away with 20 minutes remaining
Emmanuel Culio's inviting low cross from the left was diverted back across goal by Deac and Djokovic was on hand to guide the ball beyond Gordon as Celtic's run of 12 consecutive victories in all competitions came to an end
Celtic boss : "We're disappointed to lose the game but in the main very pleased with what I got out of it
 Some of my players needed the games and needed the 90 minutes
"The likes of Griffiths, Bitton, Bolingoli, Bauer and Bayo getting time on the pitch has given them minutes in their legs now
 These are huge games in the context of our season because the championship is our priority
"I thought Ntcham was unbelievable
 To give him the captaincy and then for him to take on the responsibility the way he did was excellent
 I thought his all-round game tonight was absolutely top class
"Revenge was a motivating factor in the reverse fixture as Celtic powered to a convincing 2-0 victory - but in Romania on Thursday night, the onus was on Lennon's squad members to take their opportunity to impress
The Celtic manager had called on his players to express themselves with the rare luxury of not having anything to play for on matchday six, but his shadow team, including Scott Sinclair and Nir Bitton, didn't seize their chance
Lennon was sensible in removing Christopher Jullien, the French centre-back, at half-time having conceded five fouls
 In avoiding a yellow card, he is now available for the first leg of the last-32 tie in the new year
But Cluj's proud home record, having won 10 home games in a row since losing 1-0 to Slavia Prague in Champions League qualifying in August, was rarely troubled
 Heading into the hectic Christmas period, Lennon won't have been given too much of a selection headache
Lennon opted to leave first-teamers Tom Rogic, Fraser Forster, Callum McGregor, Ryan Christie and Odsonne Edouard all at home, and Deac was allowed to showcase his undoubted ability against Celtic's second string
Deac provided both assists, meaning the 33-year-old Romanian has been directly involved in five of CFR Cluj's Europa League goals this season (two goals, three assists), providing the assist for each of the last three
The draw for the last 32 of the Europa League takes place on   in Nyon, with proceedings set to start at 12pm, UK time
Celtic return to Scottish Premiership action on Sunday when they host Hibernian at Parkhead; kick-off is at 3pm
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