A batted ball deflected off the screen and plunked the Marlins third baseman in the nose.
Bloodied and dizzy, Ramirez was replaced by Donovan Solano.
Guillen, looking to spark the offense, initially had Ramirez hitting second for the first time this year. Ramirez had anchored in the third spot.
"In the past, Hanley was a great leadoff hitter," Guillen said. "I want to get [Giancarlo] Stanton more at-bats with people on base. It's an opportunity to get him an at-bat in the first inning. Hopefully that works, at least for a little while. If that works, we will keep him there. If not, we will make another change."
Ramirez is batting .259 with 11 home runs and 37 RBIs. He last batted in the second spot on May 29, 2011.
Like the rest of Miami's lineup, Ramirez has struggled of late. He was 4-for-29 in a 1-8 homestand.
The Marlins were outscored 56-17 in the tough home stretch.
Ramirez was examined by the doctor on Friday. The hope is he will be back on Saturday.
"Right now, they're waiting for the doctor to check him out," Guillen said. "The trainer thinks it is nothing big. They want to wait for the doctor to see how he is."
After the Marlins lost 11-0 to the Rays on Friday, Guillen said Ramirez had a small break in his nose, but he is able to play. Still, he is dealing with dizziness.
"He has something, a little bit broke," Guillen said. "The doctor says he can play. But he has a headache. He's kind of dizzy. He will let me know tomorrow around noon."