Four Vikings players have not been cleared to practice at the onset of training camp.

Tight end Rhett Ellison and nose tackle Kenrick Ellis were placed on the preseason Physically Unable to Perform list on Friday, head coach Mike Zimmer announced.

Ellison continues to rehab from torn patellar tendon in his knee suffered during the Vikings' Jan. 3 win in Green Bay. Ellis' injury was not disclosed. They're both allowed to attend team meetings and practices, but have to be removed from the PUP list once they participate, per NFL rules.

Guard Mike Harris was placed on the non-football illness list and third-string quarterback Taylor Heinicke on the non-football injury list, the team announced. Harris, who started all 17 games at right guard last season, said Thursday he's been held back because of a head ailment. Zimmer called Harris' situation a "medical issue."

Heinicke is expected to miss at least two months, a source said, because of a severed tendon in his left ankle. He underwent surgery earlier this month and reported to camp in Mankato with a cast on his left leg.

How did Zimmer take the news of his backup quarterback being sidelined by kicking in the glass pane of a door?

"Darn it. Something like that," Zimmer said.

All four players still count against the Vikings' 90-man roster limit during the preseason.