The injuries that Dolphins quarterback Ryan Tannehill sustained against the Jets were not extremely serious, tests showed, but his availability for Sunday’s game at Indianapolis is uncertain.

According to a source, Tannehill sustained a bone bruise in his left knee and a bruised left quadriceps, but the MRI also revealed no structural damage.

Tannehill twice expressed optimism that he would play against the Colts — both in a postgame chat with reporters and in a private conversation with coach Joe Philbin on the flight back to South Florida, according to Philbin.

But Tannehill has been experiencing discomfort from the injuries, according to a source. And the Dolphins do not know if he will play Sunday.

Asked if he shares Tannehill’s optimism about playing Sunday, Philbin said: “I don’t know much.”

His status for Sunday will depend on how quickly he heals and how much mobility he shows in practice.

“You have to make a decision: Can the guy function and do the job asked of him?” Philbin said. “Either he can do the job or he can’t. You would love the guy to be 100 percent.”

When asked about allocation of practice snaps this week and whether Pat Devlin would get any, Philbin said: “It’s too early to predict what’s going to happen.”

One encouraging sign: Two teammates who saw Tannehill on Monday said his gait had improved and that he no longer walked with a clear limp. The Dolphins had meetings but did not practice Monday.

Tannehill sustained the injuries when he was sacked by Calvin Pace just 4:51 into the game.

Tannehill said he could have played in an emergency, but Philbin said he never considered reinserting him in Miami’s 30-9 win against the Jets.

“He wasn’t mobile enough to do the full extent of what a quarterback needs to do,” offensive coordinator Mike Sherman said.

Matt Moore replaced Tannehill and was efficient, playing much like he did when he guided the Dolphins to six wins in their final nine games in 2011.

Moore finished 11 for 19 for 131 yards, one touchdown and no interceptions. His numbers would have looked even better if Jabar Gaffney hadn’t dropped a long potential touchdown.

“I’m happy for him. The guy’s a professional,” Philbin said. “He’s extremely well-respected by the staff and the players. I’m not surprised he played well.”

Sherman said Moore gets only about 5 percent of the snaps in practice.

Sherman’s praise

“I can’t say enough about his performance,” Sherman said. “I feel comfortable calling plays with Matt that I will call with Ryan. He throws as good a deep ball as anyone. There are few teams that would have the ability to have someone like Matt come in and perform at such a high level.”

Moore said that every week he runs part of the Dolphins’ offensive game plan on the practice field, without any teammates, under the watch of assistant quarterbacks coach Zac Taylor.

“I’ll spot throw and that’s selfish on my part, but that’s what I need to get ready,” he said.

He has practiced in Miami’s no-huddle offense, but “running the no-huddle with live bullets is a little different,” Moore said. “The competition we’ve had here drives you a little bit; you want to be that much better every day.”

Intriguing matchup

If Tannehill can play Sunday, it would set up an intriguing matchup between the first player taken in this past year’s draft (Andrew Luck) and the eighth (Tannehill). Here’s how the two quarterbacks compare:

• Discounting the 18 yards in Tannehill’s abbreviated appearance Sunday, Luck is averaging more yards passing per game (281 to 242).

• Tannehill has a higher completion percentage — 59.1 to 55.6.

• Tannehill is 27th in the league in quarterback rating at 75.8, barely ahead of Carolina’s Cam Newton. Luck is 29th at 74.6, ahead of only Mark Sanchez, Brandon Weeden and Matt Cassel among starters.

• Luck has thrown more touchdowns (eight to four) but more interceptions (eight to six).

• Luck drove his team to a winning touchdown in overtime against Tennessee on Sunday, but Tannehill’s fourth-quarter numbers are better.

Tannehill is 13th in the league in fourth-quarter quarterback rating at 90.8. Luck is 29th at 69.9. Luck has three fourth-quarter interceptions, Tannehill none, though Tannehill does have one in overtime.

“Tannehill has been one of the most impressive-looking rookies to come into the league,” CBS’ Bill Cowher said.

Dan Marino ranked the top 10 first- and second-year quarterbacks on CBS on Sunday and had Luck second, behind Robert Griffin III, and Tannehill fifth, with Cam Newton and Andy Dalton third and fourth, respectively.