Guidolin’s most important match
The Italian club missed out on the group stage last year after being knocked out by Arsenal but are in a good position this time around after a 1-1 draw against the Portuguese from the first leg.
Guidolin unexpectedly guided Udine to third place in Serie A last season despite losing quality players like Alexis Sánchez and Gökhan Inler.
And this summer Guidolin’s squad has been depleted further by the departures of Kwadwo Asamoah and Mauricio Isla to Juventus, and Samir Handanovic’s move to Inter.
He told the UEFA website: "It will be my last chance and I don’t think there is anything to add other than that.
"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."
Defender Maurizio Domizzi believes the agony would be much worse if Udinese failed to qualify at the final hurdle for the second year in a row.
He said: "For me personally, it is the chance of a career. Last year was like a dream and it would have been fantastic if we’d gone through, but life went on even though we didn’t.
"To have this chance two years in a row and not take it would be much more disappointing."
Braga coach José Peseiro believes reaching the next phase of the Champions League would be an incredible achievement for the Portuguese side, who reached the Europa League final in 2011.
He added: "It is only a game of football and there are more important things, but that does not mean we don’t want to reach the group stage.
"It is a vitally important match for Braga and qualifying would be an important chapter in the club’s history."
Braga will give a late fitness test to Hélder Barbosa (foot), while Udinese’s Giampiero Pinzi is struggling with a muscle strain in his left leg which forced him to miss Saturday’s 2-1 defeat at Fiorentina