A person familiar with the negotiations says Miami Marlins manager Don Mattingly has agreed to a contract extension and will return for a fifth season in 2020.

The person confirmed the agreement to The Associated Press on condition of anonymity Thursday because the Marlins hadn't announced the deal. A news conference with CEO Derek Jeter was scheduled for Friday.

Mattingly's contract was to expire after this season. He became the Marlins' manager in 2016 and has guided the team during a rebuilding project under Jeter, who traded away All-Stars Christian Yelich, Giancarlo Stanton, Marcell Ozuna, Dee Gordon and J.T. Realmuto.

Miami Marlins manager Don Mattingly, left, shakes hands with starting pitcher Sandy Alcantara after a baseball game against the Kansas City Royals, Sunday, Sept. 8, 2019, in Miami. Alcantara pitched a complete game as the Marlins won 9-0. (AP PhotoLynne Sladky)wbb

Miami Marlins manager Don Mattingly, left, shakes hands with starting pitcher Sandy Alcantara after a baseball game against the Kansas City Royals, Sunday, Sept. 8, 2019, in Miami. Alcantara pitched a complete game as the Marlins won 9-0. (AP PhotoLynne Sladky)wbb

With the roster depleted, the Marlins this season have the worst record in the National League at 53-99, and they're set to exceed 100 losses for the first time since 1998.

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Miami Marlins right fielder Garrett Cooper, center, grimaces as a trainer checks on him and manager Don Mattingly, left, watches during the first inning against the San Francisco Giants in a baseball game Friday, Sept. 13, 2019, in San Francisco. Cooper was taken out of the game. (AP PhotoTony Avelar)

Miami Marlins right fielder Garrett Cooper, center, grimaces as a trainer checks on him and manager Don Mattingly, left, watches during the first inning against the San Francisco Giants in a baseball game Friday, Sept. 13, 2019, in San Francisco. Cooper was taken out of the game. (AP PhotoTony Avelar)