The length of Gruden's contract is not unprecedented. The Dallas Cowboys gave Jimmy Johnson (in 1989) and Tom Landry (in 1964) 10-year deals as well.
The Raiders have called a significant news conference for Tuesday, at which time they will introduce Gruden as the team's next coach, a league source confirmed to ESPN.
Gruden, who coached Oakland from 1998 to 2001 and has been working as an ESPN analyst, is returning to the Raiders to replace Jack Del Rio, who was fired after the regular-season finale Sunday.
ESPN reported Saturday that Raiders owner Mark Davis was prepared to pursue Gruden with a strong offer that could include an ownership stake in the team, which would have to be approved by NFL owners.
According to ESPN Stats & Information, only three current Raiders players have a contract with an average annual value of at least $10 million -- Derek Carr ($24.97 million), Kelechi Osemele ($11.7 million) and Gabe Jackson ($11 million).
The date of the official announcement was first reported by RaidersSnakepit.com.
The NFL on Friday said the Raiders have complied with the Rooney Rule in their coaching search.
"We believe the Rooney Rule was complied with. Minority candidates were interviewed," NFL executive vice president of communications Joe Lockhart said during a conference call. "We'll see what decision they make."
The Raiders have not identified their candidates for the head-coaching job.
Gruden will work under general manager Reggie McKenzie, who has turned down a request to interview for the Green Bay Packers' GM opening and is expected to remain with the Raiders, sources told ESPN.
Gruden will become the 12th head coach since 1960 to have multiple stints with one team, and the 16-year gap between jobs with the Raiders is the largest in NFL history for a head coach with the same team.
He had a regular-season record of 38-26 during his first stop with the Raiders and went 2-2 in two postseason appearances prior to being traded to the Tampa Bay Buccaneers for two first-round picks, two second-round picks and $8 million in 2012.
He won Super Bowl XXXVII in his first season with Tampa Bay, and he has a career 95-81 record in the regular season while going 5-4 in the postseason.
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