Only one head coaching vacancy has been filled since Black Monday, and the Oakland Raiders could be the next team to make a hire. The Raiders have interviewed several candidates to take over in 2015, but one appears to be standing out as the favorite to land the job.

Jack Del Rio may be separating himself as the most likely head coach of the Raiders. According to multiple reports, the Denver Broncos defensive coordinator has agreed to meet Oakland for a second time about taking the position. No other Oakland head coach candidate has had a second interview since the season ended in December. Del Rio is free to join the organization now that the Broncos have been eliminated from the playoffs.

The Raiders have explored hiring a bevy of coordinators and former head coaches. Mike Shanahan, Eric Mangini, Pat Shurmur and Indianapolis Colts' offensive coordinator Pep Hamilton have been among the candidates under consideration. Tony Sparano, who became the team’s interim head coach when Dennis Allen was fired in Week 4, also has a chance to coach Oakland next season. Allen also served as a Broncos defensive coordinator, making the possibility of Del Rio joining Oakland perhaps a bit more intriguing.

Del Rio has significant head coaching experience and achieved some success in his one stop. Leading the Jacksonville Jaguars from 2003-2011, he reached the playoffs twice, achieving a record of .500 or better in five of nine seasons. Del Rio has spent the last three years with Denver, helping the defense rank third in yards allowed in the 2014 regular season. Oakland ranked 21st in that category.

Oakland hasn’t had a winning season since 2002, but Del Rio may have some extra incentive to accept the job if the Raiders make an offer. He’s from northern California and played college football at USC, and has strong knowledge of the AFC West. Del Rio may also want to leave a team that appears to be in a state of flux.

Head coach John Fox and the organization agreed to part ways following the team’s playoff loss to the Colts, while there are suggestions that star quarterback Peyton Manning's future is in doubt. The next head coach of the Broncos may want to bring on new assistants and that could prompt Del Rio to seek opportunities elsewhere. Meanwhile, Broncos offensive coordinator Adam Gase is regarded as a top candidate for multiple head coach openings.

With Fox becoming a coaching free agent, he could also quickly become a hot commodity. The 59-year-old went to the playoffs in each of his four years with the Broncos, going 46-18 and reaching last year's Super Bowl. As the Carolina Panthers head coach from 2002-2010, Fox won three division titles and lost the 2004 Super Bowl.

Fox might be the No.1 candidate to be hired by the Chicago Bears, with whom he is set to interview. Fox was the Raiders defensive coordinator in 1994 and 1995, and has a much more extensive track record as a winning head coach than Del Rio. A day after leaving the Broncos, though, there have been no reports that Fox is a legitimate candidate for Oakland.

The Buffalo Bills made the first head coaching hire by signing Rex Ryan to a five-year contract. The Raiders and five other teams are still looking for a head coach.