The European champions are expected to overpower Zaragoza at Camp Nou, but then take on Massimiliano Allegri's AC Milan for top spot in Group H of the Champions League on Wednesday.

Messi arrived back in Spain on Thursday after featuring for Argentina in 2014 World Cup qualifying and despite his willingness to be involved this weekend, Guardiola said he is yet to make a final decision.

"I have not decided whether he will play or not," the coach said.

"I will decide depending on what I feel. It is true that he wants to participate. Messi is ready to play for 90 minutes. He has a very quiet life with his family. Football is what fills [the gaps]. Tomorrow we will see what the team is," he said.

One man almost certain to play is Pedro, who has missed more than three weeks with an ankle injury.

"Pedro trained with us and looks good," Guardiola said.

"We'll see how he is tomorrow and whether he can play. He trained with his team-mates and without any pain."

Meanwhile, Guardiola believes all players have a responsibility to set an example to the rest of the world when it comes to stamping out racism in football.

Coming in the wake of comments made by FIFA president Sepp Blatter, the Barca coach said: "I think we have to be very responsible to the public and the rest of the people watching us. Our behaviour has to be at the top level, and always when we work and try to make a better world to try to show to the rest of the world good behaviour."

"We make mistakes, sportsmen make mistakes because they are under a lot of pressure, but we have to correct those mistakes and keep improving, that's our responsibility in front of our supporters."

Barcelona sit in second place in the Liga standings, three points behind Real Madrid at the summit.