A day after returning to practice for the first time since collapsing last week, WR Percy Harvin was once again sitting out Thursday's practice at Mall of America Field at the Metrodome.

Harvin has missed extensive time this preseason because of issues with migraines, which caused him to collapse on the field a week ago at Winter Park.

Also not practicing today are linebackers Jasper Brinkley and Kenny Onatolu and defensive tackle Jimmy Kennedy.

Defensive end Jared Allen, who missed Wednesday's practice, is back on the field.

The Vikings traveled to the Metrodome for Thursday's practice in large part to work on the new Sportexe turf that has been installed in the building. The Vikings will hold their preseason home opener Saturday against Seattle.