Capello feels Barcelona is the team to avoid with Messi in the ranks. "Messi makes the difference. He does things that others can't even think of. Every era has its own crack player like Pele or Maradona and Messi can be the crack player of the next decade," he said.
Capello is also impressed with Barcelona coach Pep Guardiola, The Sun reported.
He has helped the Catalan club to a six-point lead at the top of La Liga and reached the Copa del Rey final in his first season in charge.
Capello added: "The Barca of Guardiola has formed a team of great potential, although in the last month they've not been as strong as they can be. At the start of the season, the way Barca played was incredible. Guardiola knew how to cope with the most difficult moments and has continued with his ideas."
"He's left important players on the bench because he was convinced the team could win anyway and things came out well for him. It's a signal that a manager has a great personality. The team has come together and formed a good group," Capello said.
Capello also hinted that United could be running out of gas in their bid for the Quintuple. "They were more fresh a month ago, but then they played many consecutive games. At this stage of the season we all have to wait a bit longer to see how each of those teams arrives at the moment of truth."