Defensive coordinator Leslie Frazier expressed hope on Thursday that rookie cornerback Chris Cook would be ready to make his NFL regular-season debut on Sunday.

All signs would point to that being a very good possibility.

Cook, who underwent arthroscopic surgery to repair a torn meniscus in his right knee in the preseason, has not been limited in practice this week and is back on the field again today. If Cook doesn't have any real soreness today or Saturday, he should be cleared to go against the Lions.

This would be excellent news for a Vikings defense that has been going with three cornerbacks in its first two games and certainly can use the 6-foot-2 Cook against Lions wide receiver Calvin Johnson (6-5, 236 pounds). The trio of Asher Allen, Lito Sheppard and Antoine Winfield is 5-foot-9, 5-10 and 5-9, respectively.

There also remains a possibility the Vikings could get Cedric Griffin back. He continues to practice on a limited basis and, coming off surgery to repair a torn anterior cruciate ligament in his left knee, should be just about ready to go. The question is: Do the Vikings want to hold him out until after their Week 4 bye or do they feel he is ready to play Sunday?

The Vikings had their entire 53-man roster on the field to open practice. This includes wide receiver Percy Harvin, who missed the Wednesday practice because of migraines and continues to battle through a strained right hip.

We'll be getting a final injury report for the week later this afternoon and that will include projections for the injured players.