The New York Yankees placed right-hander Adam Warren on the 10-day disabled list Wednesday with a lower back spasm.
The move is retroactive to Sunday and robs the Yankees of a key bullpen piece as they attempt to catch the Boston Red Sox in the American League East.
Warren, 30, is 3-2 with a 2.40 ERA but allowed at least one run in four of his last five appearances. His role had increased of late with New York shuffling the bullpen order by removing Aroldis Chapman from the closer spot.
Warren's 0.89 WHIP this season is the best mark of his seven-year career.