The Friulani have struggled this season having recorded just one win in all competitions - before this match - and were expected to find the going tough away to the English giants.
While the Italians did suffer in the first period, the second half saw them stage a tremendous comeback to take all three points and Guidolin could not have been happier.
“We played an excellent second half on a magical evening that we will always remember. Winning here has never been and never will be easy for anyone," he told reporters.
“We had already clarified everything. At half-time I tried to bring out the best in myself to reassure the lads, who I had seen a little demoralised.
"We talked for five minutes in the dressing room and also changed the tactics and did well to score after just 30 seconds. My team played with real heart in the second half."
Guidolin hopes that this victory will serve to give his team a lift ahead of their showdown with Napoli at the weekend.
"I hope this gives us a real boost in terms of results and confidence," he continued.
“We have to focus on Napoli now and it will be very tough, but right now I am just so happy. I want to share this joy with my children, who live in England and I don’t get to see very often.”