Massimiliano Allegri said Juventus were "a little bit tired" while seeing out a 1-0 win over Genoa on Monday night, the club's first game back from their winter break.
It was a workmanlike effort as Douglas Costa's goal was enough to claim all three points and draw them to withing one of leaders Napoli.
The game was the first for Juventus since Jan. 6, but Allegri said after the game that increased training during the week was the reason for the stilted performance.
"We were a little bit tired at the end of the game, more than being anxious about the result," Allegri said. "There was the desire to get a result at home and we worked very hard during the week.
"It was important to win to stay in Napoli's slipstream, and start again after the break.
"It's a challenge to ourselves, winning a seventh Scudetto would be extraordinary, beyond legendary, so we have to do well and wait for the right moment.
"The lads worked really hard during the week, and that workload made it difficult tonight. At the same time though, we didn't give Genoa anything."
Napoli boss Maurizio Sarri had earlier hit out at what he called a "gigantic mistake" in the fixture list, which has Juventus playing before his side for the next nine games in a row.
But Allegri declined to engage in the debate, saying: "It's not up to me when we play, I won't reply to Sarri who should be happy with the result [against Atalanta] and being top of the league.
"It's a beautiful duel at the moment, I have nothing more to say. There are bodies who can respond to this, I don't understand how the calendar works."
Gianluigi Buffon was again ruled out with a calf injury, but though he has been out of action since Dec. 1, Allegri said the goalkeeper will be back in training in the week ahead.
"He'll return in the week, he's ready to return and so are others," Allegri said. "He's the starter, even if [Wojciech] Szczesny is having an important season."