Massimiliano Allegri felt Juventus's dramatic win over Atletico Madrid was to blame for their first Serie A defeat of the season at Genoa.
The runaway league leaders were far from their best at Stadio Luigi Ferraris and were punished in the final 20 minutes as former Juve player Stefano Sturaro and Goran Pandev sealed a 2-0 win.
Cristiano Ronaldo was rested after his UEFA Champions League heroics against Atleti and Juve sorely missed his attacking threat in what was an insipid display.
Allegri says the effort required to overturn a 2-0 first-leg deficit against the Spanish side was to blame.
"Inevitably, the effort we put in against Atletico Madrid on Tuesday weighed on us," he told DAZN.
"We took some risks in the first half but did better after the break. Once we seemed to be in control, that's when we conceded, and the game changed.
"I expected a different Juventus. We did not put in a good performance and we made some mistakes. You can't play every game to the best of your abilities."
Juve's lead was cut to 15 points as Napoli overcame Udinese later in the day and Allegri believes the shock defeat can act as a wake-up call to this side ahead of the run-in.
"I think, if anything, this defeat can do us good and wake us up," he added.
"We thought that we'd already won the Scudetto, but that is not the case. We need another five wins and must now hope Napoli drop some points.
"It's impossible to win every game, I've said that since the start, so no need to make a drama out of it. We've played 28 games, won 24 and drawn three, so it’s not that bad."
Juventus host struggling Empoli at the Allianz Stadium after the international break on March 30.