Celtic manager Neil Lennon insists his side are still heavy underdogs despite Lionel Messi's absence from Tuesday's Champions League clash against Barcelona.

Argentina striker Messi injured his thigh in Barca's 2-0 win over Almeria on Saturday and has been ruled out for up to three weeks.

Lennon, whose side lost their Group H opener 2-0 to AC Milan, admitted it is a boost for Celtic to face Barca without Messi, but he is well aware the Spanish champions remain a formidable outfit.

"It is obviously very good news for us because he is the best player in the world," Lennon said on Monday.

"However, it is tinged with sadness because it is always fantastic to see the great players play here in Glasgow.

"We are looking forward to the game, we welcome Barcelona with open arms and we are hoping it is going to be another great occasion."

Lennon cautious

Aside from missing Messi, the visitors head into the tie likely to be without defenders Javier Mascherano, Jordi Alba and Carles Puyol.

But a cautious Lennon said: "You say that they have defensive problems with injuries but they keep on keeping clean sheets; against Rayo Vallecano, Real Sociedad and Almeria. So, regardless of personnel, they are still defending very well.

"They are unbeaten domestically, they got off to a great start in the group (4-0 win over Ajax). They are a fantastic team.

"They will be one of the favourites to win the trophy. Whether they are better than last year, you won't be able to gauge that until the turn of the year."

Brazilian forward Neymar will be charged with leading the Barca attack in Messi's absence, but Lennon does not believe the two players can be compared.

"It is like comparing a dog with a cat. They are two different types, two different players altogether," he said.

"Neymar is wonderfully gifted, quick, predominantly playing on the left-hand side and he has goals in him.

"He is only young and he has a fantastic future but it is far too early to make comparisons to Messi.

"There is only one player currently who could arguably be around the calibre of Messi and that is Cristiano Ronaldo."

Lennon, whose side famously beat Barca 2-1 in Glasgow last November on their way to the last 16 of the competition, also admitted Celtic would still regard even a point against the Spaniards as a bonus regardless of the injury to their talisman.

"Our approach will be the same whether Messi plays or not," he added.

"Barcelona don't change their system, they don't change their style of play really and 4-3-3 is just what they believe in. It has worked well for them very well over the years.

"It would be fantastic if we could get something out of it like we did last year.

"We didn't really budget for it, as it were, in both the games last year, so if we can get something it will be a huge bonus for us.

"It will be very much at times containment; to limit Barcelona to as few chances as we can and at the same time maximise the opportunities that we get, as we did last year."

Source: AFP