Tests on Ryan Clady’s left foot have led to fear of a serious injury, according to two NFL sources.

The Broncos are discussing options on how to best proceed with their All Pro left tackle. The worst-case scenario of season-ending injured reserve is a possibility.

Placing Clady on IR with the designation to return is another option. Either way, Clady will miss significant time because of a Lisfranc injury in the arch of his left foot. Lisfranc sprains occur when a metatarsal bone is displaced from the tarsus. The more severe Lisfrancs can have a three- to four-month recovery period.

A player on IR designation can return no sooner than eight weeks after he’s added to the list. In theory, if Clady is added to the IR this week, the earliest he could return is Week 11 for the Broncos’ game at San Diego on Nov. 10. More likely, if Clady is added to the IR, it would be in hopes that he is available for the final few games of the regular season and the playoffs.

The team is getting medical opinions on the extent of Clady’s injury.

Clady had signed a five-year, $52.5 million contract extension with the Broncos in mid-July. The deal included $15 million in salary and signing bonus this year.

It appeared Clady’s foot was rolled up by a fallen player late in the Broncos’ 41-23 victory Sunday against the New York Giants at MetLife stadium in East Rutherford, N.J. He hobbled badly out of the visiting locker room Sunday evening.

With Clady out, Chris Clark will be the Broncos’ starting left tackle. The Broncos and Clark reached an agreement on a two-year contract extension Friday. He signed the deal Monday.

The Broncos’ offense has scored 90 points through its first two games – both decisive victories. Quarterback Peyton Manning was not sacked by the Giants as Clady held off the likes of Jason Pierre-Paul, Mathias Kiwanuka and Justin Tuck.

Broncos coach John Fox on Monday said despite reports that tackle Ryan Clady would miss significant time with a foot injury, he would wait for the team’s medical staff to evaluate Clady’s status.

“I’m no fortune teller or into tea leaves or any of that good stuff,” Fox said. “I’m into the reporting nature of how we report the game. So right now it’s exactly what we said — it’s a left foot sprain — and when we know something (more) we’ll let all the fortune tellers know.”

When asked about his level of comfort about Clark replacing Clady if Clady can’t play this weekend against the Oakland Raiders, Fox said: “We have the utmost confidence in Chris Clark.”

The other injury Sunday was to strong safety Duke Ihenacho, who injured his right ankle. As with Clady, Fox had no further details.

“We’ll still evaluate those injuries and we’ll keep you updated as they progress during the week,” Fox said.