San Francisco 49ers' Jim Harbaugh is one of four National Football League coaches to leave their posts after the close of the regular season.
Harbaugh is likely to take the head coach job at the University of Michigan after a season which saw the 49ers win eight and lose eight games.
The New York Jets have sacked Rex Ryan, while Chicago Bears have dismissed their coach Marc Trestman.
Atlanta Falcons have also announced the departure of Mike Smith.
The Falcons had a 6-10 win-loss record this season, their second successive losing year under Smith, and lost 34-3 at home to the Carolina Panthers on Sunday.
|NFL's 'Black Monday'|
|'Black Monday' is the day after the final match of the NFL regular season, when owners traditionally sack coaches and general managers of underperforming teams|
|The term was first used in the late 1990s by newspapers in the United States|
Harbaugh leaves the 49ers with a 49-22-1 record, which includes a 20-17 win over the Arizona Cardinals in his final game on Sunday.
New York Jets owner Woody Johnson dismissed Ryan and general manager John Idzik following Sunday's 37-24 win over the Miami Dolphins. The Jets won four and lost 12 of their matches this year.
The Bears sacked Trestman and general manager Phil Emery after a 5-11 season in which star quarterback Jay Cutler struggled to find form.