SANTA CLARA  (AP) — San Francisco 49ers tight end Vernon Davis is listed as doubtful for Sunday’s game against the Green Bay Packers.

Davis left last week’s 47-7 loss to the Arizona Cardinals with a right knee injury and did not return. He attempted to practice on Thursday and Friday but left the field at the start of team drills to work on the injury with the training staff.

Davis, 31, has eight catches for 109 yards and no touchdowns through three games. He missed two games in 2014 while dealing with leg and back injuries, marking the first time he didn’t appear in at least 15 games since 2007.

“I was blocking on the play and someone accidentally bumped into my leg, kind of rolled into my leg and kinda caused my leg to strain,” Davis said.

Despite being listed as doubtful, Davis didn’t rule himself out of Sunday’s game against the undefeated Packers.

“Depends on how I feel. Feeling good? Why not?” Davis said.

The last time Davis saw the Packers he made a go-ahead 28-yard touchdown grab in the fourth quarter of a playoff game in January 2014. The 49ers won that game 23-20 on a 33-yard Phil Dawson field goal as time expired.

NOTES: RB Reggie Bush (calf) and WR Bruce Ellington (ankle) are listed as probable for Sunday after missing the last two weeks. San Francisco was outscored 90-25 in those games, with the offense entering Sunday as the league’s lowest-scoring unit, averaging 15.0 points per game.