The Serie A outfit have consistently over-performed in the past few seasons, but their coach fears the end could be in sight now
Udinese finished ahead of teams such as Inter, Roma, Lazio and Napoli to book their ticket for the qualifying stages of Europe's top competition.
However, Guidolin feels they are nearing the end of their cycle following the departure of players such as Alexis Sanchez, Cristian Zapata, Mauricio Isla and Kwadwo Asamoah over the past few years.
"It will be my last chance and I do not think there is anything to add other than that," Guidolin was quoted as saying on the official Uefa website.
"It cannot be taken for granted that this team can carry on doing so well as, to do that, we would have to be magicians and I cannot perform miracles."
Udinese held Braga to a 1-1 draw in the first leg of the Champions League play-off.