Dan Graziano examines the pectoral muscle injury sidelining Prince Amukamara for the next several weeks, and whether he has reason to wonder if the Giants will consider him worthy of a long-term deal after this season when he's eligible for free agency. (0:45)

New York Giants cornerback Prince Amukamara will miss two to four weeks with an injured pectoral muscle, coach Tom Coughlin said Thursday.

Sources earlier told ESPN's Josina Anderson that Amukamara suffered a partial tear of his pectoral muscle during Sunday night's game against San Francisco and would miss at least three to four weeks.

Amukamara sat out a number of plays against the 49ers, but he returned and finished the 30-27 victory and didn't indicate any problems afterward.

Prince Amukamara missing two to four weeks with a pectoral injury is a significant blow to a Giants defense that ranks last in the league in passing yards allowed per game (304). Wesley Hitt/Getty Images

In other injury news, wide receiver Odell Beckham Jr. stretched with the team at the beginning of Thursday's practice, then went off to the side to work under the supervision of a team trainer. He did some light jogging and some side-to-side work with a green band around his ankles, with a member of the training staff filming his movements from behind with a phone.

After a while, Beckham returned to the field, where the other wide receivers were working, and joined them for their drills, but he did not take part in any. Having Beckham on the field and moving around is an encouraging sign, although the team would like to see him go through at least part of Friday's practice before declaring him ready to go Monday, when the Giants visit the Philadelphia Eagles.

Amukamara's injury is a significant blow to a Giants defense that ranks last in the league in passing yards allowed per game (304). He said he will have another MRI in two weeks to assess the healing process but that he should be able to tell by then how it's going based on the way he feels.

"Hopefully, I don't miss much time," Amukamara said. "I'm very encouraged because I'm more mobile, I can move it around, I can still brush my teeth and stuff. If it gets to the second or third week and it's still at this stage, I'll probably start panicking a little bit."

Amukamara admitted that it's on his mind that he's playing for a contract, and he said one of his goals was to play all 16 games this year. But he said he's more disappointed to have to disappear while the Giants are getting ready to play the Eagles in a key divisional game Monday night.

"It's very tough, but the way my mind is, I've always been a team-first guy," Amukamara said. "So especially with the division the way it is, I know I'm not the only one who's excited about this year. This is a huge week, and it would have been a good game to play in."

Coughlin said Jayron Hosley would start in Amukamara's place.

"It's most unfortunate," Coughlin said of Amukamara's injury. "He's made a lot of plays for us this fall. But we'll continue on, and we will get him back."

Hosley, the team's third-round pick from the 2012 draft, has had a checkered history with the Giants and struggled when thrust into action last season. But he's responded well to new defensive coordinator Steve Spagnuolo, and Coughlin said he's performed better this year than he ever has. Hosley started in place of an injured Dominique Rodgers-Cromartie in the Giants' Week 3 victory over Washington.

"We played a game and won a game with Hosley starting at corner," Coughlin said. "He'll have to jump in there and do that, which I'm sure he's excited about."

Wide receiver Rueben Randle, who injured his hamstring in Sunday's game, was able to work during the portion of Thursday's practice that was open to the media. Defensive end Robert Ayers, who missed the past three games with a hamstring injury, also was practicing. Linebacker Jon Beason, who left Sunday's game with a concussion, still hasn't been cleared to practice but ran on the side with the trainers.