Buffalo Bills quarterback Kevin Kolb has been escorted into the locker room after slipped on a rubber mat and hurt his left knee during practice.

Kolb, is competing with first-round draft pick E.J. Manuel for the Bills' starting job, was switching fields with his offensive teammates. As he ran, Kolb slipped on a wet rubber mat and stumbled awkwardly at the Bills training camp facility in suburban Rochester on Saturday.

Though, he did not fall, he had trouble standing and put his arm around the shoulder of head trainer Bud Carpenter. Kolb then tossed down his helmet in frustration, before sitting down on the field.

Carpenter briefly examined Kolb's knee before escorting him to the locker room. Workers then began sweeping water off the mats.