"He said he felt a little better, but I don't see it right now," Rivers told reporters Monday at the team's practice, according to WEEI's Paul Flannery.
Allen missed 15 of Boston's final 20 regular season games with bone spurs in his right ankle, and was also absent from Boston's 83-74 playoff-opening loss against the Atlanta Hawks Sunday night. He remains a game-time decision moving forward, but doesn't seem to be making progress as swiftly as the Celtics hoped.
Boston shot 0-11 from the three-point arc in Game 1 and the Celtics' bench managed just four points. Considering that Rajon Rondo also faces a possible suspension, it's more clear than ever that the Celtics could use Allen's services.
Still, Rivers said nothing outside of Allen's health will dictate his return.
"If Ray's not ready, he's not ready," Rivers said. "I don't ever put a guy out if he ain't ready."