Monza clinched their first three points of the season in the first game under Raffaele Palladino, who replaced the sacked Giovanni Stroppa on Tuesday.
Serie A: Juventus is held by Salernitana while Atalanta loses the top spot to Napoli
Giacomo Raspadori fires lively Napoli striker in front of champions AC Milan
They are still in the relegation zone but a single point behind 17th-placed Verona, who lost 2-0 at Fiorentina.
“Today was amazing and unexpected,” said Palladino.
“They showed themselves to be real men … they gave it their all, I wasn’t supposed to get any of the recognition because it was all up to them.”
Troubled Juve, who lost Angel Di Maria to a direct red card five minutes before half-time, are eighth and ten points behind Atalanta after winning just two of their first seven games.
Ahead of the game, Juve chief executive Maurizio Arrivabene said it would be “crazy” to sack Allegri, who has been contracted until 2025 with a reported salary of eight million euros a year.
But a poor start in Italy and two defeats in the first two Champions League games have put Allegri in the firing line of fans who are being criticized not only for poor results but also for the boring football his side play.
Allegri was not helped by an injury crisis that denied him five potential starters on Sunday and Juve’s chances were further hampered when Di Maria – who later said the defeat was his fault – was sent off for elbowing Armando Izzo had defeated.
Juve had created little before the Argentine winger’s dismissal and Monza came closest to scoring after the break as first Dany Mota and then Gytkjaer squandered good close-range chances.
Patrick Ciurria had given Mota his chance and the Italian clipped a pass for Gytkjaer, who swept the ball home, his first goal in Italy’s top flight, causing excitement among home fans and Juve wondering where he was headed next should turn.
Atalanta regains the lead
Atalanta went top of the table after Giorgio Scalvini scored three points with a beautiful low shot 10 minutes before the break at the Stadio Olimpico.
Gian Piero Gasperini’s side are a point clear of Udinese, who beat Inter Milan 3-1 early on Sunday to claim their fifth straight game.
However, they can be joined on 17 points by either champions AC Milan or Napoli, who face off in the weekend’s headline game at the San Siro.
“It was a difficult game against a strong Roma side but we kept our form well and had too many risky moments, especially in the second half,” said Gasperini.
Roma, who lost Paulo Dybala to injury in the pre-match warm-up, were furious 10 minutes after the break when referee Daniele Chiffi didn’t give the hosts a penalty because Caleb Okoli had pulled on Nicolo Zaniolo’s trousers to the point where his Underwear was visible.
“It was a very clear penalty,” Mourinho told DAZN.
“I have to change what I’m telling the players, I have to tell them not to stay on their feet … be a clown, like a lot of people who dive in this league like they’re in a swimming pool.”
Eldor Shomurodov headed wide after a sensational game from Zaniolo with three minutes remaining and when the Uzbek captain fired a low shot just wide Atalanta secured the points.