If you didn’t think that Brad Childress’ control of the Minnesota Vikings was volatile right now, consider the latest report that he got into a heated exchange with wide receiver Percy Harvin in practice on Friday.

According to a report by Judd Zulgad and Chip Scoggins of the Minneapolis Star Tribune, Childress questioned Harvin’s effort during practice after Harvin had sat out the previous two says with an injured left ankle.

The Vikings have listed Harvin as questionable for Sunday’s game against the Arizona Cardinals at the Metrodome, and per the report he is expected to play.

In his comments to the media, though, Childress talked about Harvin.

“He's a tough guy," Childress said. "Let's face it, he injured that foot on his first catch of the game (last week at New England) and still was very productive. I would just say he's tough.”

There were rumblings about Harvin’s absence from training camp during the summer when he missed more than two weeks following the death of his grandmother. He then suffered from migraines and there were questions about why Harvin was absent for as long as he was. It’s fair to wonder if the latest flare up is an extension of Childress’ frustration from August.

If the Vikings don’t start winning now, expect plenty more little fires to start involving Childress.

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Brad Biggs covers the Bears for the Chicago Tribune