EDEN PRAIRIE, Minn.   — Brett Favre’s ironman streak has endured a litany of injuries and even a pair of premature retirement press conferences.

Perhaps this is the week that, finally, Favre’s health prevents him from playing.

The 41-year-old Minnesota quarterback has a stress fracture in his left ankle that could end his NFL-record streak at 291 consecutive games started — 315 including the playoffs.

Vikings coach Brad Childress said Monday an MRI on Favre’s foot revealed the stress fracture as well as an “avulsion” fracture in the heel bone. An avulsion fracture occurs when a fragment of bone is torn away by a tendon or ligament. Childress said neither injury requires surgery.

“He’s got great pain threshold and also great competitive zeal,” Childress said, succinctly summing up Favre’s legacy of durability.

Favre is also the subject of an NFL investigation into allegations that he sent lewd photographs and suggestive messages to a female New York Jets employee in 2008, a development that first put his streak in danger with the possibility of a suspension under the league’s personal conduct policy. NFL spokesman Greg Aiello said Monday there was nothing to report about the investigation.

For this week, it appears Favre’s biggest problem will be figuring out a way to heal fast enough to face New England on Sunday.

“He’s got to be able to do all the things that his position does,” Childress said. “You can’t put a guy that’s a sitting duck out there. His competitive nature I’m sure will come into it. But a lot of times you’ve got to protect people from themselves.”

Favre had arthroscopic surgery on the ankle in May, and he received a series of lubricating injections in the joint at the beginning of the season. The ankle has bothered him at times this fall, but he hurt it in Sunday’s 28-24 loss at Green Bay as he was being tackled from behind while throwing his first of three interceptions against the Packers.

Favre was limping around during the game and walking gingerly afterward, and Childress said he was wearing a walking boot around the practice facility on Monday to make him more comfortable.

He refused to rule Favre out of this week’s game, which would likely mean a start by Tarvaris Jackson. But he also insisted that the streak won’t influence the decision on whether to play him against the Patriots (5-1).

“We have to do what is right for the Minnesota Vikings,” Childress said. “That’s what I get charged with at the end of the day. I’m not worried about someone getting one more start or one more yard to equal 300.”

His teammates will have to believe it when they see it.

“Unless they cut his leg off, it’s going to be hard to keep him off the field,” defensive tackle Kevin Williams said. “That’s the type of guy he is, from what he’s shown throughout his career.”

The Vikings (2-4) are struggling to find the groove they enjoyed in Favre’s first season, which started 6-0 and ended in the NFC championship game. With Favre’s turnover count now at 14 — including 10 interceptions, already three more than last year — he has been hurting them as much as he’s helped them so far.

Favre didn’t enter the locker room at Winter Park when it was open to reporters on Monday, but after the game he said he wouldn’t put his record ahead of common sense.

“If I can play but not be effective, then it’s not worth playing,” Favre said. “I hope I use good judgment, so we’ll see. I’m no spring chicken anymore. I don’t heal as quickly.”

The injury news overshadowed a second day of Childress criticizing Favre’s decisions on the interceptions, two of which the Packers turned into touchdowns. The other stopped a Vikings drive that was already in field-goal range.

Childress said he planned to speak with Favre about the issue of staying “within the confines of our system,” as he put it after the game, an assertion Favre didn’t disagree with.

Asked Monday whether he and Favre are on the same page with their strategy, Childress paused for a second before saying, “Absolutely.” When asked if Favre’s straying from orders was a recurring issue, Childress said it was isolated to Sunday night.

“There was a couple ’night at the improvs,”’ Childress said. “That happens. It’s just a matter of it’s with merit.’

Childress said he doesn’t have a “breaking point” where Favre’s turnovers force a non-injury benching.

“When I invited him back here I said, ’Just as long as we don’t throw 33 interceptions and seven touchdowns, I think we’ll be OK,”’ Childress said. “I would hope it doesn’t flame up to those proportions, where we flip the whole thing.”

Childress also suggested that Favre’s struggles will make it easier for them to agree about how the offense is run.

“My experience with quarterbacks is always when they are a little more humbled, they are always much more receptive,” he said.