SANTA CLARA -- Quarterback Colin Kaepernick is listed on the 49ers' injury report as probable for Sunday's game against Arizona with an undisclosed foot issue.

Kaepernick has practiced in full throughout the week, as was the case before the Sept. 22 game against Indianapolis, when he also was listed on the injury report with a foot problem. He had seven carries for 20 yards in that 27-7 loss.

"We don't really talk about what it is he's working through," coach Jim Harbaugh said Friday. "We're complying with the rules, and he's on the report. We haven't altered anything with the practice or game plans."

Kaepernick has had only four carries in the past two games combined. He remains the 49ers' second-leading rusher behind Frank Gore, with 27 carries for 154 yards and no touchdowns (and thus no "Kaepernicking" celebrations).

Whatever the ailment is, Kaepernick is walking and running without any hindrance. He was in socks after Friday's practice in the locker room while shooting baskets into a mini-hoop with teammates Demarcus Dobbs and Nnamdi Asomugha.

"He's taken just as many reps in practice every single practice," Harbaugh said.

So why is he on the injury report?

Responded Harbaugh: "I think you know why. It's been well documented about the injury reports, any type of ailment, injury or however you define it, has got to be on the injury report. We're complying with the rules."

  • Defensive tackle Ray McDonald is listed as questionable after practicing Friday for the first time this week, doing so with a support sleeve on his injured right biceps.

  • Linebacker Patrick Willis (groin) also is questionable, as are defensive tackle Justin Smith (shoulder), right tackle Anthony Davis (shoulder), right guard Alex Boone (shoulder), cornerbacks Asomugha (knee) and Carlos Rogers (knee) and center Jonathan Goodwin, who did not practice Friday because of an illness believed to be the flu.

  • If the best receiver on the 49ers' practice field isn't Anquan Boldin or Vernon Davis, it could be Chuck Jacobs, at least in how he's supposed to perform his scout-team role.

    Jacobs, the practice squad's only wideout, is used each week to mimic the opposing team's top receiver.

    "I'm every great receiver we go against. I'm that guy," said Jacobs, who's doubled this week as Larry Fitzgerald of the incoming Cardinals. Other receivers he's mimicked: Jordy Nelson (Packers), Reggie Wayne (Colts), Chris Givens (Rams) and Andre Johnson (Texans). He won an in-house, player-of-the-week award for his role as Givens.

    "He does a nice job, kind of the 'featured guy' each week," Harbaugh said of Jacobs, who caught a winning touchdown pass two months ago, albeit in an exhibition game at Kansas City.

    Jacobs (6-foot, 178 pounds) was a three-sport star at Kennedy High in Richmond before attending Laney College in Oakland and then transferring to Utah State, where he excelled as a receiver and return specialist.

  • The Cardinals classified Fitzgerald (hamstring) as questionable after he practiced in full Friday for the first time this week.

  • 49ers wide receiver Quinton Patton (fractured right foot) is the only player listed as out.

  • Offensive lineman Patrick Omameh got signed by the Tampa Bay Buccaneers off the 49ers practice squad.

  • Former defensive lineman Michael Carter, one of Bill Walsh's self-proclaimed top draft picks ever, will be the 49ers' honorary pregame captain. He's representing the 49ers' 1988 comeback win over the Minnesota Vikings.

  • This is alumni weekend for the 49ers, and festivities include a bocce ball tournament, a health seminar, a tour of Levi's Stadium, the 49ers Hall of Fame ceremony Saturday in which former executive John McVay will be enshrined, and Sunday's halftime recognition.

    For more on the 49ers, see Cam Inman's Hot Read blog at blogs.mercurynews.com/49ers.