There's a report on cfl.ca that Winnipeg Blue Bomber running backs Fred Reid (second in rushing yards) and Carl Volny are both done this year with ACL injuries after the Toronto game. Since the Bombers rely on running, especially on first down, that's gotta hurt. Winnipeg has won two more games than the Cats and hold the tie breaker over the Cats with six games left. Normally it would be unlikely for the Cats to end up more wins than the Bombers, but with the injuries Winnipeg could implode down the stretch.
One caveat, running backs in the CFL are a fungible commodity, so finding a new one won't be that hard (De'Andra Cobb?). Reid was one of the better running backs in the CFL, so replacing him with someone close to his ability will be tougher.