The 39-year-old feels the Argentina international is in a league of his own and has questioned his compatriot's ability to outshine him.
Much is expected of the Brazil international following his fine performances at the Confederations Cup, but Sylvinho thinks his 21-year-old compatriot could end up playing second fiddle to Messi.
"Neymar is Brazil's best player at the moment and one of the best in the world. But to outperform Messi, who has won the Ballon d'Or four times, will be very complicated," Sylvinho told Fox Sports Brasil. "Ronaldo, Romario and Ronaldinho, three very impressive players, all didn't achieve such a feat.
"And there's much more to Barcelona than just Messi. They also have [Andres] Iniesta and Xavi. It will not be easy for Neymar."
Sylvinho won three Liga titles and two Champions League trophies during his time at Barcelona from 2004 until 2009.