Coach Brad Childress said after practice that "it's hard for me to even handicap" whether Harvin can play Sunday.
Harvin began suffering symptoms of migraine headaches Thursday.
"They all vary in intensity and time period," Childress said.
Harvin spent Friday at home, Childress said.
"So we'll just have to see how he comes along," Childress said. "It's less than ideal, but he's played under the same circumstances this year."
Kevin Seifert covers the NFC North for ESPN.com.