Guidolin, whose side are unbeaten after seven games and visit erratic Napoli on Wednesday, wrote off Udinese's title chances after their 3-0 home win over Novara on Sunday sent them to the summit.
"We can't fight for the scudetto," Guidolin, whose side have 15 points and are the only unbeaten team in Serie A alongside Juventus, told reporters.
"None of the other coaches have mentioned Udinese among the possible title winners and I trust my colleagues, they understand football.
"In the dressing room, we have a notice with our aim, which is to reach the 40 points needed to avoid relegation, so we are still 25 short.
"We will enjoy it for one day but we have no reason to get carried away."
Udinese finished fourth last season but were given little hope of a repeat performance after selling two key players, winger Alexis Sanchez to Barcelona and midfielder Gokhan Inler to Napoli, in the close-season.
However, with striker Antonio Di Natale, last season's league top scorer with 28, still knocking in the goals they have looked as good as ever.
Napoli have given priority to the Champions League and their league form has been wildly unpredictable, with striker Edinson Cavani still to score away from home.
They have beaten both AC Milan and Inter Milan, yet their last two games have seen a home defeat by Parma and goalless draw at Cagliari.
"We have to be more clinical, we have been making too many mistakes," said coach Walter Mazzarri.
"If you look at the other sides fighting for the top places, when they create four chances they convert two of them."
Juventus, third with 13 points, kick off the midweek round on Tuesday when they host Fiorentina having drawn four of their last five matches.
Champions Milan, up to 11 points after winning their last two games, are at home to Parma on Wednesday while Inter visit Atalanta.
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