Ray McDonald sits out practice

SANTA CLARA, Calif. -- Ray McDonald will have to get used to playing with pain the rest of the season, but he didn't suffer Wednesday.

The San Francisco 49ers kept their standout defensive tackle out of practice. He is expected to play Sunday against visiting Arizona.

McDonald sustained a partially torn bicep at the top of his muscle Sunday night during the 49ers win over the Houston Texans. He is not at serious risk of further damaging the bicep, although he will have surgery after the season.

"Hard to predict that right now, how it's going to affect him the entire season," San Francisco coach Jim Harbaugh said Wednesday. He feels good about it. The doctors feel good about their evaluation and we'll trust in that."

Starting inside linebacker Patrick Willis was limited, but he practiced in pads for the first time since injuring his groin in Week 3. If Willis doesn't have a setback, he should play against the Cardinals.

Quarterback Colin Kaepernick re-appeared on the injury report with a foot injury. He practiced fully Wednesday just as he did when he appeared on the report earlier in the season. Kaepernick has not shown any visible signs of being bothered by the injury.