Jorge Sampaoli has been sacked by Sevilla after a poor run of form left them just two points above the relegation zone in LaLiga.
A 2-0 defeat at fellow strugglers Getafe on Sunday proved the final straw for Sampaoli, who had only returned for his second spell in charge in October.
Sevilla have won just twice in their past seven LaLiga matches, losing four games in that run.
Sampaoli did steer Sevilla into the quarter-finals of the Europa League, but a different coach will now be in the dugout when they go head-to-head with Manchester United.
A Sevilla statement read: "Sevilla have terminated the contract of coach Jorge Sampaoli after the team's defeat in Getafe, which has once again placed the team on the verge of relegation places.
"The fact that the team has not managed to get out of the lowest positions in the table since his incorporation as coach and the image offered in the last matches of the team have led the club to make this decision, in search of a reaction in the 12 games that remain in the league.
"Sevilla thanks Sampaoli for the services he has provided and wishes him the best of luck in his future."
The club said they planned to appoint a new coach later on Tuesday, to be in charge in time to take an early-evening training session. Former Real Valladolid and Eibar boss Jose Luis Mendilibar has been strongly linked with the job.
Sampaoli was first put in charge in Sevilla ahead of the 2016-17 season and led them to a fourth-placed finish in LaLiga before leaving to take over as Argentina head coach.