Lennon could barely contain his simmering fury at the post-match media conference, branding Celtic’s display as unacceptably weak.
Neymar was Celtic’s principal tormentor, grabbing a hat-trick and his first Champions League goals as Barcelona topped Group H and left Lennon’s men rooted to the bottom of the section with just three points.
It was the first time Celtic had conceded six goals in any fixture since losing 6-0 to Kilmarnock in 1963. Last night’s scoreline matched the heaviest ever margin of defeat suffered by Celtic in their 51-year history of European football, joining the 5-0 humiliation at the hands of Artmedia Bratislava under Gordon Strachan in 2005.
Regardless of Barcelona’s outstanding performance, Lennon was in no mood to try to deflect the level of embarrassment experienced by Celtic.
“Barcelona were fantastic, as we expected them to be, but we were very poor,” said Lennon.
“For some of the players, that was an unacceptable performance. It was nowhere near reminiscent of the performances we’ve put in previously against Barcelona and that’s very disappointing.
“There was no bravery on the ball tonight. We started off nervously and it looked like our heads went down at 2-0. We changed it up and went more defensive – going 4-5-1 – but that didn’t stop the blood flowing.
“We were weak, and that’s not been like us. That’s something I’ll need to address and I need to look at going forward.
“There were only three or four players who showed anything – Virgil van Dijk, Adam Matthews and Mikael Lustig, along with Fraser Forster in goal who I’d excuse as well.
“The rest of the team were very poor and well below the standards they’ve set themselves over the last few years. We came here on the back of two great results at home and with an idea of finishing the group with a positive result and performance.
“But I got neither. I didn’t get the performance and I certainly didn’t get the result. I’m angry and disappointed but it’s something I have to get over very, very quickly. I’ll have to analyse it and look at the character that was there tonight. There wasn’t much of it.”
Lennon insisted his tactics and team selection were not to blame for the defeat and explained the absence of regulars Charlie Mulgew and Kris Commons from his starting line-up.
“There was no difference to how we approached the previous games against Barca, we set the team out exactly the same way,” he said.
“Looking at them before the game, I sense a little bit of quiet among them so we tried to get them motivated before they went out there. You could see straight away there were some really loose passes in difficult areas and we didn’t play anywhere near our strengths.
“I wouldn’t say some players gave up, but it certainly looked that way. I’d never accuse a player of doing that, but there were a lot of half-hearted performances out there. As a manager, that’s the most disappointing aspect of the whole game.
“Charlie wasn’t 100 per cent fit. He has a groin problem and didn’t train this morning. Speaking to the medical team, he wasn’t ready to start. As for Kris, we just wanted more pace down the flanks. We put Pukki up top and wanted the full-backs bombing forward. But we didn’t achieve any of that.
“Some players didn’t do their jobs which they were assigned to do. We looked very open in the second half through the middle. That’s not normally an accusation you can throw at the players, especially the two centre-halves who have been wonderful for us this season. They were done by very good movement and passing.”
Celtic’s struggles in the Champions League this season are in stark contrast to their run to the last 16 of the tournament last year. The summer sale of key players Victor Wanyama and Gary Hooper has clearly diminished Lennon’s side but he accepts the situation Celtic find themselves in as a selling club.
“Wanyama and Hooper were two of my best players, if not the best, and we sold them for significant sums of money because they are excellent players,” he added.
“I have to build the team again and we look to the rest of the season now and qualification for the Champions League again.
“It’s a balancing act which is very difficult to achieve sometimes. You don’t really know if you are guaranteed qualification – then you maybe get two weeks to try and find the right type of player after that. Players sometimes won’t come unless you have Champions League football guaranteed. Then, after that, it’s pretty difficult to try and get the kind of player you want in the two week window. So I totally understand the balancing act that we have to do.
“Is it more difficult for Celtic to compete at this level of the game? No. Last season we made the last 16 and we have done that three times in the last 13 or 14 years.
“It’s imperative for us as a club going forward that we try to achieve qualification for the competition each year. Then actually when you go through you release the purse strings a little bit more.
“But I have got good players I want to work with. I want to make them better and want them to learn from the experience they have gone through this year. Hopefully that will stand them in good stead for next year.
“It is a sore one tonight. I am hurting a little bit, as are the players. We have to get over it very quickly, because we still have a lot to play for this season.”