As the Minnesota Vikings went through training camp this month, Brett Favre remained in Mississippi, beginning to feel the twinge of doubt he had dreaded with his first two retirements. So when Vikings Coach Brad Childress, whom Favre had spurned just three weeks ago, called out of the blue Monday to ask, once and for all, if he wanted to return, Favre’s response was simple: “Can I play Friday?”

And so Favre, serial retirer, unretired for the second time in less than two years Tuesday, joining the Vikings for a contract that ESPN reported was worth $12 million this season and $13 million in 2010  if he does not retire again.

The Vikings had courted Favre, a three-time league most valuable player, throughout the off-season but were left empty-handed on the eve of training camp when Favre said he would not play.

When Favre initially said he would not come back, Childress said he thought the Vikings’ interest in him was finished. That did not last long, and on Tuesday, perhaps to make sure Favre would not change his mind again, Childress picked him up at a small airport in St. Paul.