Mike Shanahan has had discussions with the Buffalo Bills and San Francisco 49ers about their head-coaching positions, according to reports.

The Bills have been in contact with Shanahan, the former head coach of the Denver Broncos and Washington Redskins, and hope to set up an interview with him, Adam Schefter of ESPN reported Saturday.

The Bills’ job came open after former coach Doug Marrone opted out of his contract Wednesday. According to ESPN, the Bills also requested permission to interview Indianapolis Colts offensive coordinator Pep Hamilton. Because the Colts don’t have a bye in the playoffs, Hamilton won’t be allowed to interview for another position until his season with Indianapolis comes to an end.

Ian Rapoport of NFL Network reported Friday that the 49ers are expected to interview Shanahan this weekend. The 49ers’ officials already planned to be in Denver this weekend to interview Broncos offensive coordinator Adam Gase.

The 49ers are looking to fill the opening created when Jim Harbaugh and the team parted ways after last Sunday’s season finale and he was named head coach at Michigan this week.

—The Oakland Raiders asked the Denver Broncos for permission to interview defensive coordinator Jack Del Rio for their head-coaching job, according to reports Saturday.

The interview with Raiders officials reportedly took place in Denver on Saturday. Del Rio is in his third season as the Broncos’ defensive coordinator. Denver ranks third in total defense this season.

Del Rio was the head coach of the Jacksonville Jaguars from 2003 to 2011 and had an overall record of 69-73. He twice led the Jaguars to the playoffs but managed only one postseason win. Del Rio, 51, is a Bay Area native, and his parents are longtime Oakland season-ticket holders, according to ESPN.com. Two sources close to him say Del Rio covets the job.

—The New York Jets were expected to interview former Buffalo Bills head coach Doug Marrone on Saturday, according to multiple reports.

Owner Woody Johnson and consultants Ron Wolf and Charley Casserly reportedly were meeting with Marrone as the Jets seek a replacement for Rex Ryan, who was fired on Monday. Marrone became one of the Jets’ top candidates after he opted out of his contract with the Bills on Wednesday.

—Wide receiver A.J. Green on Saturday was declared out of the Cincinnati Bengals’ playoff game on Sunday at Indianapolis against the Colts.

Green sustained a concussion in the fourth quarter of a 27-17 loss at Pittsburgh last Sunday night. He practiced with the Bengals on Thursday before missing Friday’s workout. He originally was listed as doubtful.

Green, who had eight catches against the Steelers, was playing despite a deep biceps bruise. He leads the Bengals with 69 receptions for 1,041 yards and six touchdowns, but missed part or all of four games because of a toe injury.

—Carolina Panthers running back DeAngelo Williams was active for Saturday’s NFC wild-card game against the Arizona Cardinals.

Williams, the Panthers’ all-time leading rusher, missed the last four games with a fractured hand suffered against the Minnesota Vikings on Oct. 30. Jonathan Stewart has rushed for 486 yards in the last five weeks for the Panthers, starting the last four games. He got the start against the Cardinals.

—Pittsburgh Steelers strong safety Troy Polamalu, who missed the last two games because of a knee injury, will start against the Baltimore Ravens on Saturday night in the AFC wild-card game.

Polamalu was able to practice all week and he was listed as probable on the Steelers’ final injury report. Coach Mike Tomlin did not commit to the eight-time Pro Bowler starting until late in the week.

The Steelers will be without running back Le’Veon Bell, who was ruled out against the Ravens because of a hyperextended right knee. Rookie Josh Harris will start in place of Bell.

—The San Francisco 49ers signed defensive lineman and former British Olympian Lawrence Okoye to a reserve/future contract.

The 6-foot-6, 304-pound Okoye was on the team’s practice squad this season. He spent his rookie season of 2013 on injured reserve. Okoye, 23, competed in the 2012 Summer Olympics for Britain, finishing 12th in the discus throw.

The 49ers also signed running back Kendall Gaskins, tight end Xavier Grimble, wide receiver Lance Lewis, offensive tackle Chris Martin and defensive tackle Garrison Smith to reserve/future contracts.