by Rachel Shuster, USA TODAY Sports

Boston Celtics point guard Rajon Rondo, arguably the team’s most valuable player, wasn’t suited up today for the big home game against the Miami Heat and the first time facing ex-Celtics guard Ray Allen at home.

Just before tipoff the Celtics said Rondo was heading for New England Baptist Hospital for an MRI on a hyperextended right knee. Courtney Lee started in his place.

Rondo was hurt late in the double-overtime 123-111 loss at the Atlanta Hawks. He got some treatment Sunday, went through the walkthrough but then left for the MRI.

Rondo is averaging 13.7 points, an NBA-leading 11.1 assists and 5.6 rebounds and posted triple-doubles the past two games.

Another change, apparently not injury-related: Rookie Jared Sullinger replaced Brandon Bass.

Allen, as usual, did not start for Miami. He entered the game with 4:39 left in the first quarter, to a mild round of boos as he replaced Mario Chalmers.

Allen came to the Celtics, with Kevin Garnett, in 2007-08 and helped Boston win its record 17th NBA championship.

The Celtics entered Sunday on a six-game losing streak, the longest in the Garnett era.

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