Inter coach Walter Mazzarri apologised to the club’s fans following an embarrassing 4-1 defeat at home to Cagliari on Sunday.

The Nerazzurri went into the clash unbeaten but were thoroughly humbled by a side that had taken just one point from their opening four Serie A matches.

In an explosive first half, Dani Osvaldo cancelled out Marco Sau’s opener, before Inter completely imploded when captain Yuto Nagatomo was sent off for two bookable offences as Albin Ekdal scored a 15-minute hat-trick.

The result left Inter stunned and Mazzarri hopes lessons can be learned from the episode.

“We’re sorry for the fans, who are suffering as we are,” he said.

“I got a few decisions wrong regarding squad rotation and did not look at how much energy we would expend, which is crucial in the modern game.

“When things go badly like that it all contributes to everything else going worse.

“A more experienced team that goes down to 10 men becomes compact and waits for the things to blow over. We’ll all learn from this lesson. We don’t need to discuss it too much.”

Cagliari could even afford to miss a penalty while 3-1 ahead, with midfielder Andrea Cossu’s spot-kick saved by Samir Handanovic following Nemanja Vidic clumsy challenge on Sau in the area.

It was the second time this season Vidic has given away a penalty following his move from Manchester United in the summer.

Playing for the third time in eight days on Sunday, Mazzarri admitted he may have been expecting too much from the 32-year-old Serbian defender.

“I perhaps also made a mistake with Vidic by playing him too much,” he added.

“I take responsibility for it. There are players that can’t take three consecutive matches in this period.

“Is it physical or mental? A combination of the two.”