The Catalonia-born midfielder has been handed the squad captaincy by Luis Enrique ahead of the competition but his place in the squad is now in jeopardy following the latest update.
According to report from BBC Sport, the veteran La Blaugrana schemer has been forced to pull out of Spain final friendly warm up game against Lithuania in midweek with growing speculation over the next step.
Enrique’s squad all tested negative following a round of mandatory testing in the last 24 hours but Busquets will now enter into self-isolation.
The RFEF have confirmed they plan to field a selection of players from their U21 squad against Lithuania as part of an extended measure to prevent potential infections.
Spain are set to begin their Euro 2020 campaign with a Group E opener against Sweden on June 14 in Seville.