Fiorentina confirmed the decision after their third consecutive defeat, a 2-1 home loss to Torino on Saturday in which they surrendered the lead. Earlier defeats against Roma and Frosinone had already put Grosso under pressure, but few expected the club to act so quickly.
The result was particularly disappointing after Fiorentina invested around 130 million euros in the summer transfer window. The club brought in 13 new players as part of an ambitious rebuild following a campaign in which they only secured Serie A survival with two games remaining.
Grosso had been appointed in June after his spell with Sassuolo, with sporting director Fabio Paratici choosing him to lead the club's rebuilding project. The expectation was that the revamped squad could push towards the European places.
Instead, Fiorentina's poor start has forced an immediate change of direction.
The decision also came as a surprise because the club had initially appeared ready to continue backing Grosso. No Fiorentina official spoke to the media after the Torino defeat, despite growing frustration among supporters.
Fiorentina have yet to announce Grosso's replacement, but Paolo Vanoli has been linked with a return to the club.
Vanoli took charge in November last season after Fiorentina endured a difficult start to the 2025/26 campaign and spent much of the season battling near the relegation zone. He guided the team to a 15th-place finish before being released at the end of the season.
Fiorentina now face Venezia at the Stadio Pier Luigi Penzo on Friday, with the club needing an immediate response after a turbulent opening to the campaign.