Johnny Manziel clearly does not think he's got a drinking problem ... 'cause the Cleveland Browns QB was chugging champagne right from the bottle in Miami on Wednesday.
Manziel and his girlfriend Colleen Crowley were sitting poolside at a Miami hotel ... sippin' away under the sun on Veuve Clicquot Rose'.
At one point, someone handed Johnny what appears to be a mixed drink -- and he took that down too.
Interesting move ... considering he's been under fire for reportedly missing an official team treatment session following a night of hard-partying.
In fact, ESPN's Skip Bayless went on the air and said he's convinced Manziel is an alcoholic after speaking with several people in the Browns organization.
Clearly, Johnny isn't fazed.