The Bianconeri have failed to win in three games since Di Natale stopped scoring and the 35-year-old's missed penalty effectively meant two points went to waste in last weekend's goalless draw with Bologna, with the club dropping to ninth as a result.
Guidolin remains optimistic his side can improve across the last eight games regardless, but any addition to Di Natale's 15-goal haul against the Flying Donkeys would be more than welcome.
He told La Repubblica: "If he'd scored that penalty we wouldn't even be discussing this.
"It's true, he's not been hitting the standards we're used to seeing from him, but we have to stay calm.
"The team is in good physical condition and their motivation is still very strong.
"I am dreaming of guiding the club into Europe for the fourth time but it will not be easy as there are a lot of good teams ahead of us.
"We have to maintain the same spirit and high level of performance."
Midfielder Giampiero Pinzi is Udinese's only injury concern while Chievo have their doubts over defender Nikos Spyropoulos with Marco Andreolli, Dario Dainelli, Boukary Drame and Isaac Cofie all serving one-match bans.
Gialloblu boss Eugenio Corini was disappointed to take nothing from a 1-0 home defeat to AC Milan, but he was impressed by his players' continuing resolve to guarantee another season in Serie A as they now enjoy a nine-point cushion to the drop zone.
"I'm really proud of my boys and I have great confidence we will reach our goal," he said. "We are in a favourable position although we still need to get more points as soon as possible.
"Now we go to work against Udinese who are a tough side, but with our current desire I am sure we will do good things."
Chievo have not won at the Stadio Friuli since November 2008 - their first visit since achieving a second promotion from Serie B.