The 27-year-old ace was whistled by a section of the Nou Camp as he was substituted during the second half the 3-0 Champions League home win against Lyon because of what they felt was a lacklustre performace.
Ronaldinho did not look pleased about being replaced for the third straight match by Barcelona coach Frank Rijkaard.
"I don't understand why they whistled him. He's the best in the world and a key player in the team," said Argentine striker Lionel Messi.
"He's an incredible player," added Barcelona's new recruit Thierry Henry who acknowledged that Ronaldinho had not been in top form during the team's recent away matches.
The Spanish sports press appear unanimous on their appraisal of Ronaldinho's dip in form, but some appear to believe his star is on the wane.
El Mundo daily on Friday said Ronaldinho is no longer "untouchable" while Barcelona-based La Vanguardia said the player was "in torment".
Ronaldinho could be paying the price for his reported behaviour off the field too. Catalan newspaper La Vanguardia added that 48 hours before Barcelona's goalless draw against Osasuna at home on Sunday Ronaldinho was seen at a a famous nightclub in the city.
"No one understands" the decline in form of the 2005 FIFA World Player of the Year award, conservative daily newspaper ABC added.
Written by: AFP