The Blaugrana supremo believes that Atletico Madrid will push the Spanish champions all the way, while he is refusing to rule Real Madrid out of the running either
The reigning champions currently top the table ahead of this weekend's action, but only on goal difference from Atletico Madrid, while Real Madrid are just five points further back in third.
Rosell has been hugely impressed by the form of Diego Simeone's men this season and also remains very wary of the threat posed by the Rojiblancos' city rivals.
"Consistency is the key and Atletico under the tutelage of Simone have been performing very well this season," the Blaugrana supremo told reporters in Kenya on Saturday.
"No doubt it promises to be one of the toughest campaigns in many years. Atletico have proved that. I can see it going down to the wire.
"Approaching the half way mark and having the same points as them says it all and as Barcelona we are determined to defend the title but can not rule out other teams.
"I predict that any of the three teams can lift the trophy. The question is who will hold it the longest."
Meanwhile, Rosell once again intimated that the club are willing to make Lionel Messi the best-paid player in the world - even though the Argentine only signed a new deal in February of last year.
"The best player in the world deserves the best contract," he reiterated.