BOSTON (CBS) — There was another injury concern down at Gillette Stadium on Monday.

Last week, it was wide receiver Julian Edelman who had New England fans holding their collective breath after he left practice with a foot injury. Edelman returned to the practice field the next day, providing Patriots fans with some relief.

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That relief lived until Monday afternoon, because another key element to New England’s offensive attack left the field with an injury. This time it was All Pro tight end Rob Gronkowski, who exited Monday’s joint practice session with the Chicago Bears after the first play of 7-on-7 drills:

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It doesn’t appear that the injury is anything serious, but any time Gronkowski leaves the field there is concern.

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Monday was the first of three joint practice sessions the Patriots will host with the Bears this week, leading up to Thursday night’s preseason game at Gillette. Gronkowski did not play in New England’s preseason opener against the Saints last Thursday, and hasn’t played in a preseason game since 2012.