Parma started the season with ambitions of securing a Europa League place but a 2-1 home defeat to Catania saw Donadoni's men beaten in their fourth game from five.
Sixth-placed Fiorentina are now 10 points away and beating a resurgent Sampdoria presents a daunting prospect for a Parma side who have proved to be mentally fragile since December.
Donadoni told La Repubblica: "From a psychological standpoint we failed to react properly and we found ourselves at the mercy of Catania's best technical players in the middle of the park.
"We reacted quite well in the second half and largely controlled the game but we have to do that from the first minute of the game and not leave it late to desperately salvage a result.
"I am still convinced, however, that we will have no trouble reaching our goals.
"There is certainly something weighing on our minds and we need to shift that at a difficult time, but we can only do that through playing football."
McDonald Mariga, Ishak Belfodil, Fabiano Santacroce and Daniele Galloppa face late fitness tests as Parma search for a first win in eight attempts.
Meanwhile, Sampdoria's upward trajectory continues under the stewardship of Delio Rossi but the Blucerchiati are "not safe yet", according to his assistant Fedele Limone.
Samp, who are now unbeaten in five, climbed above tomorrow's opponents Parma and into the top half of the table with a 2-0 victory over Chievo but Fedele is targeting at least three more wins between now and the end of the season.
He said: "We are not safe yet, we need at least nine more points - with a tally of 41 we could perhaps afford ourselves a sigh of relief."
Samp are unbeaten at the Marassi in 2013 but, against Chievo, star striker Mauro Icardi failed to score for the first time in the new year.
"When you achieve great results the important thing is the performance of the whole team, we don't like to talk about individuals," Fedele added.
Defender Gaetano Berardi is Rossi's only injury concern, while this week also saw Edoardo Garrone become the new club president following the death of his father Riccardo last month.