Allen (hip) has been ruled out for Sunday's game against the Pistons, Danny Cunningham of 850 ESPN Cleveland reports.
Allen lasted just 12 minutes in Friday's loss against the Bucks, and the big man is set to miss his first contest since a two-game stretch between Nov. 13 and Nov. 16. The Cavaliers are dealing with several injuries right now, but Robin Lopez seems like the prime candidate to see an expanded role while Allen remains out. Allen's next chance to play will come Monday at Toronto in the second half of this back-to-back set.