EDEN PRAIRIE, Minn. -- Minnesota's Percy Harvin missed practice for a second straight day Thursday because of a migraine headache.
Coach Brad Childress said the wide receiver and kickoff returner was visiting a doctor again after his absence on Wednesday.
"Just under the weather," Childress said, adding: "Whatever you do to make it through these things."
Harvin is also dealing with a sprained left ankle he suffered in the Oct. 31 game at New England and played through last Sunday against Arizona.
After being held out of Wednesday's practice, quarterback Brett Favre was participating on a limited basis on Thursday. Favre said taking last Wednesday off might have helped rejuvenate his body a little as he fights ankle, foot and calf problems.
Wide receiver Sidney Rice could play at Chicago this Sunday, but Childress has been noncommittal. Rice, trying to complete his comeback from hip surgery, went through a hard practice on Thursday, experiencing "a few tweaks" and normal soreness, according to the coach.
Childress said he wanted to see how Rice's body responded on Friday, and the Vikings have until Saturday to decide whether to activate him for the game from the physically unable to perform list.
Also, cornerback Asher Allen has not been practicing because of a concussion. Rookie Chris Cook would start in his place on Sunday if Allen can't play, and Childress said Allen has been struggling to recover this week.