Barcelona's Carles Puyol
Barca are in pole position after back-to-back victories and can now take a significant step towards qualifying for the last 16 if they come out on top against Celtic who managed a surprise win away to Spartak Moscow in their last game to leave them second on four points.
Despite regular centre-halves Carles Puyol and Gerard Piqué having spent most of the season in the treatment room, Barca have been a model of efficiency.
Although they haven't reached the peak of recent campaigns in terms of performance, only the El Clasico draw against Real Madrid has stopped them from boasting a perfect winning Liga record.
Messi once again showed his importance to the team with a hat-trick at the weekend as Barca beat Deportivo La Coruna 5-4 and he now already has 15 goals this season.
His tally for the calendar year is up to a remarkable 71.
<strong>Tiredness</strong>
Barca dismissed any fears of tiredness as they stormed into a three-goal lead away to Deportivo but a harsh penalty awarded for a foul by Javier Mascherano allowed the Galician side back into the game.
In the end they were left holding on for the final 10 minutes with just a goal advantage and down to 10 men following the dismissal of Mascherano for a second yellow card.
Xavi Hernandez and Pedro Rodriguez started the game on the bench as they were given a break ahead of the visit from Celtic but coach Tito Vilanova didn't risk dropping Messi who had been on international duty with Argentina.
But the World Player of the Year is also expecting to become a father for the first time in the coming days which could affect his availability against the Scottish champions.
With Puyol and Piqué still not fully fit, it's likely that Mascherano and Alex Song will be the centre-half pairing against Celtic although Adriano Correia was chosen ahead of the Cameroon international against Real Madrid due to his pace.
Puyol remains sidelined with a dislocated elbow, while Piqué is still struggling with an injured left foot sustained against Spartak in mid-September, with the club explaining: "He has stayed at the gym to do specific work."
<strong>'Pragmatic approach'</strong>
Dani Alves at right back is also injured and so youth product Martin Montoya should keep his starting position. In midfield, Sergio Busquets will be missing through suspension.
Celtic warmed up for the clash with a 5-0 victory over St Mirren and manager Neil Lennon then flew to watch Barca in action against Deportivo.
"It will be awesome if we can get something out of the match but it won't be great if we lose the game," he said.
"I'm taking a pragmatic approach and we are not going to get carried away by the surroundings, that is for the supporters. The players have to go there and compete and do themselves justice."
Lennon feels the team has grown as the season has gone on.
"We weren't great at the start. We had the [Champions League] qualifiers which were our short term aim but now we are in there the players are believing that they are good enough to play at that level." – AFP