The Chicago Bears are likely to be without an important part of their secondary for a few games.
No timetable for his return has been reported, but it is likely that he will miss at least a game or two.
Callahan, 27, has appeared in all 13 games and made 10 starts this season. He was off to the best start of his career, matching career highs with two interceptions and six passes defensed, as well as a career-best 43 tackles.
He was a restricted free agent this past offseason, and the Bears signed him to a one-year, right-of-first-refusal RFA tender worth $1.9 million.
Veteran Sherrick McManis replaced Callahan on Sunday. Undrafted rookie cornerback Kevin Toliver also was on the field a bit Sunday night.
The 31-year-old McManis is in his ninth season with the Bears, and most of his playing time has come on special teams. He did pick up an interception in the third game of the season against Arizona. McManis had seven total tackles (six solo) and one quarterback hit on Sunday.