"Ray is feeling lot better," Rivers said. "We told him to stay away, you know, we don't need anyone else getting sick."
Asked about Allen's availability for Friday's game, Rivers replied: "I think he'll play but I have no idea."
Allen missed Wednesday's victory against the New Jersey Nets due to illness, allowing Keyon Dooling to earn his first start since joining the Celtics this season. The Celtics overcame a slow start to hold New Jersey to 35 points in each half and pull away for an 89-70 win.
Rivers said that Mickael Pietrus "looks great" in workouts and is expected to join the team's practices next week. The Celtics have four days off after playing the Pacers Friday, which could be a good time to integrate Pietrus if he is healthy enough to participate in practice sessions.