Oliver Provstgaard opened the scoring in the 37th minute, heading home after Mattia Zaccagni’s delivery. Gustav Isaksen doubled Lazio’s lead with a precise finish in the 66th minute, before Fisayo Dele-Bashiru completed the victory with a solo counter-attack in the 89th.
Spalletti, watching from the stands while suspended, struggled to explain Juventus’ performance and insisted that tactical adjustments would mean little without a change in mentality.
“It becomes pointless to talk about a particular department or player, because those things come afterwards. What matters here is intensity, spirit and heart. Everything else comes after that.
“We have shown fragility, and it starts in the head, not in the legs. We need to find the motivation, because that is where fragility takes shape. You start chasing the game and fail to recognise what is coming.
“Everyone in football has good feet. What makes the difference is what you see in advance and how you think ahead. A formation, or having one more striker, changes nothing without hunger, courage and character.”
The Juventus manager also accepted that his own approach needed examining after another disappointing result.
“I am worried. I have to ask myself questions because we are getting worse, and I need to analyse things, especially my own work. The first thing everyone should do is talk about themselves.
“We were all below the required level. Nobody can claim to have saved face and then speak about somebody else. Defeats involve everyone, and nobody escapes responsibility.”
Gattuso, by contrast, was keen to keep Lazio’s feet on the ground after a commanding performance in Turin. The visitors combined defensive discipline with direct attacking play to punish Juventus at key moments.
“We have to live day by day. I have known these players for three months, and we know only the path of hard work. We must think one match at a time, but we are doing something incredible. The road is long,” he said.
Gattuso also praised the commitment required to execute his approach, with Lazio prepared to build from the back and commit players forward.
“The team has courage, and if you want to play this way, you have to go at a thousand miles an hour. It is demanding, but it brings benefits.”
Lazio’s victory kept them level on 19 points with Inter at the top of the table. Juventus, meanwhile, were left with urgent questions to answer after failing to turn their spells of possession into a meaningful response.