SANTA CLARA, Calif. -- Already awaiting tight end George Kittle's return from knee and ankle injuries, the San Francisco 49ers will now also be monitoring the progress of their other top receiving option.

Niners coach Kyle Shanahan announced Tuesday that wide receiver Emmanuel Sanders suffered some cartilage damage in his ribs against the Seattle Seahawks on Monday night. X-rays taken at Levi's Stadium were inconclusive, leading Sanders to have an MRI on Tuesday morning.

The results of further testing revealed the cartilage damage, which Shanahan said will put Sanders' availability for this week's game against Arizona up in the air but isn't something the Niners expect to be a long-term issue.

"He'll be day-to-day and probably end up being a game-time decision," Shanahan said.

Sanders was hurt early in the game but attempted to play through it. Those efforts ended early in the second quarter when Sanders departed for the locker room and did not return.

The 8-1 Niners traded for Sanders on Oct. 22 with hopes that he could be the missing piece the offense needed to push them to Super Bowl contender status. Sanders wasted no time making an impact, posting 14 catches for 137 yards and two touchdowns in his first two games.

Sanders had a pair of catches for 24 yards before leaving Monday's game with the injury. Kittle was a pregame inactive with his knee and ankle injuries and it's possible he could be out again this week, as Shanahan said that nothing has changed about his status from last week.

Without Sanders and Kittle, the 49ers offense struggled to find a rhythm and the replacement pass catchers struggled with drops against Seattle.

"They're our two best playmakers so it definitely takes a toll," Shanahan said after the game. "We knew that coming in with George, we kind of realized that was going to happen today. And Emmanuel was out there battling, had that happen with his ribs. He tried to go a few more series longer but he had to go out. Other guys came in and some guys stepped it up at times. We just didn't have the consistency there."

In other, more serious, injury news, 49ers defensive lineman Ronald Blair III will miss the rest of the season with a torn ACL in his right knee. Blair has been a key backup, accumulating 14 tackles and three sacks while playing all over the line. The Niners plan to work out some free-agent edge rushers in the next couple of days as potential replacements.

Left tackle Joe Staley, who made it through his first game back from a broken fibula without any issue, has a broken finger and is seeking a second opinion. Shanahan said Staley could require surgery that would cost him a couple of weeks.

Defensive tackle D.J. Jones, who left Monday's game with a groin injury, is expected to miss at least a week and linebacker Azeez Al-Shaair will be in concussion protocol before he can be cleared to return.

Like Kittle, kicker Robbie Gould will again be questionable throughout this week and a game-time decision as he works back from a quad injury. Running back Matt Breida also aggravated a previous ankle injury and will be considered day-to-day.

As for rookie receiver Jalen Hurd, who is on injured reserve with a back issue, he is eligible to begin practicing this week. However, Shanahan said they monitored his workouts last week and Hurd did not "meet the requirements" the training staff had set forth to open his practice window, so he does not expect Hurd to begin practice this week.

The 49ers do not have to decide on Hurd's status in the immediate future as they still have both designations for players on injured reserve available.