Dorival was only appointed 14 months ago, but a 4-1 defeat against rivals Argentina proved to be his last game.
Tension is rising in South Sudan after the vice president is put under house arrest.
Experts say there are parallels between attempts to expel pro-Palestinian student protesters and Bush-era deportations.
The six-time winner beat Grigor Dimitrov 6-2, 6-3 to reach his first Miami Open final since 2019.