The Serie A champions went into Sunday's match unbeaten against the Viola at Stadio Artemio Franchi since 1998, and that run looked like it would continue as they went into half-time two goals up through Carlos Tevez and Paul Pogba.
But it was a completely different story after the break, with Giuseppe Rossi grabbing a hat-trick and Juve coach Conte was at a loss to explain the defeat.
"I think the game was practically closed. We were in control in every way, even in the second half and had some more great chances to add to our tally," he told Sky Sport Italia.
"Then something strange and unthinkable happened. We lost a match that we had been dominating. How do we explain it?
"In 10 minutes we destroyed all the hard work, both during and before the game. We managed to allow Fiorentina back into it and concede odd goals.
"This is football. We have to take these 10 nightmare minutes and learn from them. I continue to say this year will be very, very difficult.
"In these 10 minutes we did everything to help Fiorentina get back into the match, more than they had been at any stage. There are huge regrets.
"We struggled more last season and got a draw, whereas this time until the 70th minute it was all Juventus. This is football, nothing can be taken for granted."
With a Champions League tie against Real Madrid coming up on Wednesday, it had been suggested that Conte's men had let their concentration wander, but the 44-year-old did not feel that this was the case.
"This was an important game in a fiery atmosphere, so we could not be distracted by Real Madrid," Conte said.
"We were in the match from the start and only went wrong in those 10 minutes.
"It has happened a few times this season that we’ve conceded chaotic goals. We have to work on it. That is all."