Internazionale coach Walter Mazzarri has apologised to fans after the home defeat against Cagliari.
Striker Marco Sau put the visitors ahead inside the first ten minutes of the game but Dani Osvaldo responded straight away only for Albin Ekdal to strike three times after captain Yuto Nagatomo was sent off.
It means the Nerazzurri fail to close the gap at the top of the table as they now lie fourth, seven points from leaders Juventus and Roma.
"I made a mistake in adopting rotation the way I did for the game," Mazzarri said after the game.
"I failed to understand the energy consumption which is pivotal in today's game.
"[For example] Vidic, I used him way too much but I assume my responsibilities, there are players who simply cannot play three games in a row at this stage of the season.
"We did slightly better in the second half. [The red card?] It's not easy to comment when you lose 4-1, maybe one of the two yellow cards was harsh.
"We are sorry for the fans, they suffer just like we do.
"But we will all learn from today, it's not time to talk but to act, straight away, on Thursday in the Europa League."
