The injury, if serious, means that one of the most vital members of the Packers secondary will likely miss time. This is terrible news for a Green Bay defense that struggled last night to stop the Saints, who scored 34 points in their loss.
His replacement, Jarrett Bush, started only one game last season. While he is a part of the Packers' defensive rotation, he does not have the skills necessary to be an equivalent replacement for Williams, who is one of the top corners in the league.
Without Williams on the field, the Packers will have to rely on Bush and veteran Charles Woodson. Woodson, in his 14th NFL season, has seen both his production and speed decline with the years. Williams' absence would significantly change the tenor of the Packers secondary.
It is unknown, as of now, what the nature or the severity of Williams' injury is, and therefore it is hard to speculate how much time he may miss. Considering that he appeared to be in significant pain last night, it does not bode well, and he will likely be out for some time.
Packers coach Mike McCarthy will be addressing the media at 4:00pm EDT today and is expected to address Williams' injury. Until then, it is hard to say how much time—if any—Williams may miss.