A statement on the club website said the 30-year-old forward, beset by drinking, depression and weight problems in recent years, would be warned for his absence "in line with the clause established in his contract".
His spokesperson responded with a statement saying Adriano was simply having a day off and would train later on Tuesday.
"After a sequence of daily training, Adriano asked to rest on Monday," it read, adding that the player had visited the sprawling Vila Cruzeiro favela (shanty-town), where he was raised, and was involved in a minor traffic accident.
"During a visit to the community, his car and a motorbike touched each other. As the two were travelling slowly, nobody was injured."
The former Brazil and Inter Milan forward, whose career has been in steady decline since the 2006 World Cup, signed a performance-based contract with Flamengo two weeks ago.
Adriano left Corinthians in March, after failing to get match fit.
On rejoining Flamengo, the Rio de Janeiro club where he began his career in 2000, he promised to score lots of goals, saying: "You can count on me."