The Bianconeri are in crisis after the 1-0 defeat at Chievo sent them plummeting to fifth place in the Serie A standings.
"Saturday evening is a crucial game for us," admitted defender Chiellini. "Either we get back on our feet or we sink without trace.
"It can be the turning point, but I certainly did not expect at this stage of the season to see Roma in front of us.
"Now is really not the right moment to face the Giallorossi, but the three points are crucial to get past them again."
On Monday the club confirmed its faith in Coach Ciro Ferrara following a three-hour summit meeting.
"We are going badly and the responsibility is above all that of the players," confessed Chiellini.
"Nobody is against the Coach, in fact we are all on the same boat and trying to help him.
"Unfortunately we still haven't found a solution to this negative moment and, even if we have worked very hard, the results have not been positive."