Cardiff City’s promotion push has been dealt a worrying blow after Rubin Colwill limped off just 20 minutes into Saturday’s 3-0 win over Northampton Town, with manager Brian Barry-Murphy fearing a “serious” ankle injury. br br The 23-year-old Wales international was forced to leave Sixfields on crutches after going down awkwardly, and early signs suggest ligament damage that could keep him sidelined for an extended period.