Sevilla sacked head coach Jose Luis Mendilibar on Sunday following a run of just two wins from their opening eight games of the La Liga season.
The 62-year-old Basque manager helped steer Sevilla away from relegation when he was appointed in March.
He also led them to a seventh Europa League title, earning qualification to this season’s Champions League.
Sevilla will host league leaders Real Madrid on 21 October before facing Arsenal in the Champions League.
“Sevilla have decided to relieve Jose Luis Mendilibar of his duties as the club’s head coach following the results at the start of the season,” said the club in a statement, with the Andalusian side 14th in La Liga after Saturday’s 2-2 draw at home to Rayo Vallecano.
“The club would like to thank the Basque coach for his services, whose role will go down in the club’s history after winning the Europa League in Budapest.”
Mendilibar helped Sevilla beat Manchester United and Juventus en route to last season’s Europa League final, where his team won on penalties against Jose Mourinho’s Roma to extend their own record number of titles.
They have drawn both their opening Champions League games – against Lens and PSV Eindhoven – and sit third in Group B, one point and one place behind Arsenal.