As career records go, Neil Lennon's at Camp Nou stands up to pretty close scrutiny. In two visits, the Northern Irishman remains undefeated. Celtic's current manager was a player with the Scottish club when they ousted Barcelona from the Uefa Cup in 2004. Lennon and his teammates claimed an unlikely second-leg scoreless draw in Catalonia, despite an onslaught of Barcelona pressure.

Eight months later, Lennon again donned green and white as Celtic earned a Champions League group stage point at the home of the team now widely regarded as the best in world club football.

Still, Lennon's ability to impart valuable advice and experience on his players ahead of Tuesday evening's Champions League match is, the manager believes, offset by the current status of Barcelona. In the eight years Lennon has progressed from midfield general to a highly promising young manager, Barcelona have simply set about influencing an entire generation.

"When I played against Barcelona it was in the pre-Lionel Messi days," Lennon recalled. "Xavi was already in the side but he was young and [Andrés] Iniesta was on the cusp of the squad. Since then, those three have been the key instruments in why they have been so successful. Put those three in any team and I suspect they would turn them into world beaters.

"They hadn't really reached the heights when we played them. It was the following year they won the Champions League and I think that was the springboard for all the success they have had since. The challenge facing my team is bigger than it was back then. This Barcelona team is two or three gears better than anything I have seen before."

In characteristically stark terms, Lennon warned: "These guys are baby-faced assassins. They will eat you alive if you give them half a chance. They will rip you to shreds. They come across as really nice guys, but they are absolute footballing animals."

For Celtic, this is unfamiliar territory. It is exceptionally rare for them to be such strong underdogs in any match, even in Europe. In the specific case of Lennon, there is the rare emotion of fear over the possibility of a heavy defeat.

"Listen, they make great teams look ordinary," Celtic's manager said. "It's a totally different set up for me as a coach.

"The normal instincts of the players will be curtailed. Not by choice – just by the sheer force of the players they are going to come up against. There is anxiety there. I've thought about nothing else. You are wary of being embarrassed. You don't want that, I certainly don't want that.

"Everyone says it's very exciting going there, but these guys have to go out and play against them. They have to be totally focused for 93 or 94 minutes and it won't be enjoyable at times. It possibly won't be that enjoyable for myself. The build up is great, but from here on in it's just total concentration."

Celtic can take heart from their opening two Group G games. A home point against Benfica was followed up by an impressive away win over Spartak in Moscow. From Lennon, one message has been consistent; he is not content with the role of a bit-part player even in such surroundings as Camp Nou. "We have come here more in hope than expectation but we have nothing to lose," he added. "We are not here for a holiday or for tourism. We are here to play football.

"We will respect them, but we will have to play aggressively at times as well. I won't be in the tunnel when the teams walk out, but I just want my players to look straight ahead, not look at the side, and try to focus on getting a foothold on the game at some stage."

Any concern in the Barcelona ranks could only stem from a relative shortage of options in defence. Dani Alves, Gerard Piqué and Carles Puyol remain injured, meaning the 21-year-old Marc Bartra could start at centre-half.

Tito Vilanova is also minus the services of Sergio Busquets, who is suspended, but Messi continued his prolific form with a hat-trick, watched first-hand by Lennon, during Saturday night's 5-4 win at Deportivo La Coruña.

Against Celtic, Barça will be seeking their 100th Champions League win along with, more pertinently to Vilanova, the imposition of daylight between them and the rest of the group.