The Camp Nou side have a commanding six-point lead over Atletico and sit 11 points clear of Real Madrid, but the Spain international insists much could still happen between now and the end of the season.
“It is early to talk about rivals for the title. The two clubs will be there, though, so it seems,” Xavi told reporters.
“We do not forget Madrid, though, despite the distance they are behind us. There is still a long way to go in the league.
The 32-year-old then spoke about the upcoming clash with Diego Simeone's side, admitting that he has been impressed with their consistency to date.
"Sunday’s game is one of the most attractive fixtures of the season and this year even more so seeing how Atletico are doing," he added.
“Atletico are very strong. It was said that they would fail, but they have made few mistakes so far. This Sunday there is a chance that we could drop points.
"They have lost only twice in the league, they have a good dynamic and they have [Radamel] Falcao, who makes a difference. Hopefully people will enjoy it on Sunday.”