Rajon Rondo has been diagnosed with a torn ACL in his right knee, the Boston Celtics announced on Sunday afternoon.

Rondo will miss the rest of the season and a surgery date is to be determined.

Rondo sat out Sunday's game against the Miami Heat with what the Celtics called a hyperextended right knee, which he suffered in Friday's double-overtime loss to the Atlanta Hawks. Now, Rondo, who was voted as a starter for the Eastern Conference All-Star team, will rehabilitate a gruesome knee injury.

Rondo averaged 13.7 points, a league-best 11.1 assists, and 5.6 rebounds per game this season. In his final two games of the campaign, Rondo notched triple-doubles.