Garcia has MRI on right forearm
Garcia experienced pain and swelling in his right forearm after practicing Wednesday and had an MRI on Thursday morning after it continued to bother him.
"That's exactly what it is, a bruise," coach Dennis Erickson said. "We'll see how it is. He'll play in the football game (Sunday), but it's a day-to-day thing."
Erickson said Garcia injured his arm during San Francisco's 24-17 victory last week over the Detroit Lions, but apparently did not realize the extent of the injury until participating in Wednesday's drills.
Garcia has started 61 consecutive games for the 49ers and is listed as probable for Sunday night's game at in Seattle Seahawks.
Garcia, who wore a brace on his right wrist and forearm as he watched practice, did not speak with reporters Thursday.
"I thought he threw it pretty good (Wednesday)," Erickson said. "You'd like to have him out there. He's been around long enough that it wouldn't affect him as much as it would others."
Backup Tim Rattay took all the snaps with San Francisco's first-team offense in practice.
Garcia also has been hampered this season by back and groin problems. The NFL's all-time leader in touchdown passes-to-interception ratio entering the season, Garcia has thrown six touchdown passes and seven interceptions while San Francisco has struggled to a 2-3 start. He ranks just 27th in the league with a 67.4 passer rating after three straight seasons of finishing among the NFC's top four quarterbacks.
PLUMMER NFC'S BEST: Cornerback Ahmed Plummer was announced as the NFC's Defensive Player of the Week after his performance against Detroit. Plummer had an interception and knocked down two other passes against the Lions. Plummer leads the team and ranks fourth in the NFC with three interceptions.
The fourth-year cornerback has 24 passes defensed since the start of last season -- ranking him sixth in the league during that span. Plummer bulked up to 198 pounds in the offseason, about 15 more than he weighed last year, and he said that has made him stronger and more confident.
"Ahmed's been a solid player for a good three years now, and I think people are finally starting to take notice upon him," Niners defensive coordinator Jim Mora said. "If he can keep making plays on the ball and have big games like that, then people will continue to take notice."
TE JOHNSON COULD MISS SEASON: Erickson said for the first time that it's possible tight end Eric Johnson could miss the remainder of the season because of a broken clavicle he sustained in an Aug. 23 exhibition game against New Orleans.
The Niners originally expected Johnson would be able to return by mid-November and play in the team's final six games.
"That's kind of an iffy thing now," Erickson said. "They take a bone scan every week. It's starting to mend, but we were hoping it would heal faster than it has. In another week or two, we'll know more whether he'll even be able to play this year or whether we'll have to put him on" injured reserve.
Erickson said Johnson, the team's starting tight end since his rookie season of 2001, has lost almost 20 pounds since being injured. It could take weeks for Johnson to get back in playing shape after he is cleared to practice.
"If you're only going to have him back for the last two or three games, it's not worth it," Erickson said. "There's some roster things we can probably do with that spot. But we're going to wait a couple weeks to see where we're at."
EXTRA POINTS: All-Pro receiver Terrell Owens returned to practice after missing Wednesday's session with an Achilles strain. ... Receivers Arnaz Battle (hamstring) and Tai Streets (quadriceps) and cornerback/kick returner Jimmy Williams (back) were added to San Francisco's injury list Thursday. All are listed as probable. ... Seattle coaches ought to know the 49ers system well. Seahawks head coach Mike Holmgren was a San Francisco assistant for six years, defensive coordinator Ray Rhodes was a San Francisco assistant 12 years, linebackers coach John Marshall spent 10 years with the 49ers and defensive line coach Dwaine Board coached the past 13 seasons with the Niners before joining the Seahawks this year.
This story is from ESPN.com's automated news wire. Wire index