Franck Ribery starred as Fiorentina piled more misery on the under-fire Marco Giampaolo with an emphatic 3-1 victory over sorry 10-man AC Milan on Sunday.

Giampaolo is only six Serie A games into his Rossoneri tenure but a fourth league defeat in a lifeless performance will do little to quieten rumours his position is already under threat. 

The hosts trailed at the break thanks to Erick Pulgar's penalty and Mateo Musacchio's dismissal for a poor challenge on the sublime Ribery severely hit Milan's chances of salvaging a result. 

Gaetano Castrovilli scored a first Serie A goal to ensure the game was up for Milan and possibly Giampaolo, while a saved Federico Chiesa penalty preceded a deserved goal for Ribery and a Rafael Leao consolation late on.

Fiorentina threatened first when Ribery teed up Chiesa for a first-time shot that almost squirmed under Gianluigi Donnarumma, who eventually saved with his head.

It was Ribery's brilliance that led to the opener. The veteran's quick feet flummoxed Musacchio and, although his one-on-one shot was saved, Ismael Bennacer tripped Chiesa on the follow-up.

Pulgar clinically found the bottom-right corner from 12 yards and Milan were fortunate not to go two behind when Castrovilli's goal was ruled out, as Chiesa needlessly strayed offside.

The situation worsened 10 minutes into the second half when Musacchio was sent off - via a VAR review - for a rash, high-studs lunge on Ribery.

Fiorentina then doubled their lead through Castrovilli, who smashed home after Donnarumma could only parry Chiesa's cross.

Donnarumma ensured another reckless Bennacer challenge, this time on Castrovilli, was not punished as he saved Chiesa's spot kick.

But Fiorentina coach Vincenzo Montella celebrated a resounding three points against his former club when Ribery twisted and turned before drilling into the bottom-left corner, Leao's excellent solo effort to open his Milan account doing little to sour the visitors' delight.

What does it mean? San Sir-woe for struggling Giampaolo

It seems pretty harsh for a head coach to find himself under pressure just six competitive games into a job, but that's the very predicament Giampaolo finds himself in. Gennaro Gattuso has been linked with a shock return, while Luciano Spalletti and Claudio Ranieri are thought to be under consideration. Milan were devoid of ideas and static with the ball. Giampaolo needs more and fast.

Ageless Ribery marvels in Milan

He may now be 36 but Ribery is still an absolute Rolls Royce of a footballer. On countless occasions it appeared the ball was glued to his feet as he sauntered past defenders with ease time and again. The energy and movement of Chiesa, lined up alongside Ribery in Fiorentina's attack, meant the ex-Bayern Munich star always had an outlet and even the home fans applauded his late goal. A standing ovation followed when he made way for Rachid Ghezzal in the 89th minute.

Musacchio and Bennacer typify hapless Milan

There were several poor performances for Milan, but Musacchio had already been embarrassed by Ribery in the build-up to Fiorentina's first goal before his shoddy tackle on the veteran winger drew a deserved red. Bennacer gave away two penalties in an outing he will want to forget quicker than he might be allowed to.

What's next?

Milan need to quickly inject some spark into their season and will hope to do so at Genoa on Saturday. Fiorentina play a day later at home to Udinese.