Massimiliano Allegri thinks Juventus "paid for their inexperience" as his young side missed the chance to secure the Serie A title after SPAL staged a second-half comeback to win 2-1.
A draw would have been enough for the table-topping Juventus to record an eighth successive Scudetto, and they appeared to be on course when Moise Kean took the lead for the visitors in the 29th minute.
But SPAL struck back twice in the second half against a much-changed Juve – who have one eye on next week's Champions League clash with Ajax – with Kevin Bonifazi heading home before Sergio Floccari cleverly controlled and fired into the net to secure all three points for the home side.
"We wanted to close it today," Allegri told the club's official website after the game.
"The boys' performance was good and the young players competed with such authority.
"On the second goal we made a bit of a mistake, but we had a great first half and a good reaction.
"Everyone did well, we're only sorry for the defeat, but we paid for inexperience."
Allegri made nine changes from the side which drew 1-1 against Ajax on Wednesday, naming debutants, Grigoris Kastanos and Paolo Gozzi in his starting XI. Juve host Ajax in the return leg of the Champions League knockout tie on Tuesday.
On the changes, the Italian manager said: "If we had put all our starters in, it would have been easier to win it, but there is the goal to obtain on Tuesday.
"We have made 27 victories, three draws and two defeats and this is an impressive record."
The Juventus boss said he expects to have Sami Khedira, Blaise Matuidi available on Tuesday, with the latter missing out against SPAL with cramp, while Douglas Costa will be assessed ahead of the Champions League tie.
Juventus' experienced defender Andrea Barzagli called time on his career after playing 81 minutes of the defeat at SPAL, and announced his decision in the post match press conference.
Barzagli said: "When you are a footballer you find it hard to think about life after football, but this season's injuries helped me to understand. I've decided to quit in June."
On the SPAL match he added: "We wanted to wrap it up today, also because we had a good game with so many guys going forward in the first half."
