"AS Roma announces that it has relieved Mr Zdenek Zeman of his position as coach of the first team," a club statement said.
"The team has been temporarily entrusted to Mr Aurelio Andreazzoli."
Friday's defeat was the latest in a line of embarrassing results for Roma, who have yet to win this year and find themselves in eighth place on 34 points, nine behind local rivals Lazio in the third Champions League spot
They are also three points behind AC Milan, who are fifth and occupy the second Europa League slot.
Zeman was brought in with much fanfare to replace Luis Enrique in the close season after the Spaniard presided over a disappointing season.
However, the Czech-born coach has failed to challenge for the title or the Champions League places, both season's objectives.
While their attacking play can often be exceptional, his team have conceded 42 goals so far this season, more than any other side apart from 17th-placed Pescara.
The fans finally turned on him after Cagliari's fourth goal on Friday, with hardcore fans in the Olympic Stadium displaying a banner that read "Boemo (Bohemian, Zeman's nickname) out", before turning their backs on the game.
After a meeting in Rome on Saturday morning between club directors and the owner James Pallotta, the decision was taken to relieve the coach of his duties.
"We decided to sack Zeman because we thought it was the only decision to take," sporting director Franco Baldini told reporters after the meeting.
"He's not the only one responsible, but for now we can only change the manager.
"We have faith in Andreazzoli, he knows the players well as he's been here for years, which means we don't lose nore time with him getting to know the players.
"After talking it over with the owner and the management we thought it was the right decision."
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