Big man Isaiah Hartenstein joined the Thunder via free agency this offseason.

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OKLAHOMA CITY – Oklahoma City Thunder center Isaiah Hartenstein will be out at least a month after suffering a small, non-displaced fracture in his left hand during a preseason game in Denver.

The Thunder said Thursday that Hartenstein, who was injured in Tuesday’s game, will be reevaluated in five to six weeks.

The Thunder added the 6-foot-1, 250-pound Hartenstein as a free agent in the offseason to help them with rebounding and their lack of volume, two of their few weaknesses last season as they earned the No. 1 seed in the play Western Conference off-offs. He averaged 8.5 points, 7.8 rebounds and 3.5 assists for the New York Knicks last season.