The veteran midfielder insists his teammate remains the world's best player but admits the "stratospheric" achievements of Cristiano Ronaldo and Franck Ribery pose a threat.
Messi, Xavi's teammate at Barcelona, has won the past four editions of the prestigious individual award and is once more one of the favorites to emerge victorious this year, despite struggling with injuries for much of the current season.
However, while he maintains the Argentina international is still the world's best player, Xavi believes the 26-year-old could struggle to seal a fifth-straight prize based on the form of rival players this year.
"If we ask ourselves who the best player in the world is, then it has to be Messi, there's no question about that," he told Sport. "But if we ask who has been the best player in 2013, then I admit there is more of a debate to be had. The fact Messi has won it four years in a row could end up damaging him when it comes to voting.
"I would always give it to Messi, because he is the player that wins matches by himself, although you have to recognize that Ribery and Cristiano have reached stratospheric heights in terms of goals and assists. Ribery won everything, and Cristiano [Ronaldo] has notched up an incredible amount of goals. If I were captain of Spain and had a vote, I'd vote for Messi first, then Ribery, and then Cristiano. [Arjen] Robben would also be worthy of my vote."
The winner of the 2013 Fifa Ballon d'Or will be announced January 13.