Ellis recorded 11 of his points in the fourth quarter as the Mavs notched a sixth victory in seven games.
Dirk Nowitzki registered 18 points and six rebounds for Dallas, which broke a 66-66 tie with an 8-0 run midway through the final period to put the game away.
The Pacers got 13 points and 10 rebounds from Lance Stephenson in dropping a second in three games.
George Hill added 14 points and Paul George provided 12 with seven rebounds.
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