Juventus dropped points in Serie A for the first time this season as Genoa held them to a 1-1 draw in Turin on Saturday.
Cristiano Ronaldo's first-half strike was cancelled out by Daniel Bessa as the visitors ended a five-game top-flight losing streak at the Allianz Stadium.
The result gives Napoli the chance to close to within four points of Juve at the top of the table and sees their 11-game winning run in all competitive competitions come to an end just three days before they face Manchester United in the Champions League.
Ronaldo received a player-of-the-month award before kick-off and continued his good recent form with the opening goal, becoming the first player to score 400 goals in Europe's top-five leagues in the process.
But Bessa's header rescued a draw after some slack Juve defending and means Massimiliano Allegri's side no longer have a perfect record in 2018-19.
Ronaldo looked a threat from the off, forcing Ionut Radu into a good save before rattling the woodwork with a powerful header.
He eventually found the net 18 minutes into the game, tapping home from inside the six-yard box after Radu had been wrong-footed by Joao Cancelo's deflected shot.
Juve seemed eager to score a second as soon as possible, but struggled to convert their possession into meaningful chances, and Wojciech Szczesny had to be alert to deny Krzysztof Piatek an equaliser from distance.
Genoa's growing confidence was rewarded after 67 minutes. Christian Kouame picked up a loose ball when Juve's defence assumed it was going out for a corner, and his cross was met by the unmarked Bessa, who headed home from six yards out.
Allegri introduced Paulo Dybala off the bench and both he and Miralem Pjanic fired narrowly wide from distance, but Genoa withstood the late pressure to move into 10th in the table and give Napoli the chance to close the gap to the leaders.
What it means: Juve confidence knocked ahead of United trip
Allegri's side had won 11 games in a row in all competitions before Saturday's game, but they have only themselves to blame for failing to claim their ninth Serie A win of the season here. They seemed to become complacent after going ahead and Genoa deserved their equaliser, a goal that means Napoli could close to within four points of the leaders if they beat Udinese. It also offered United a glimpse of vulnerability ahead of Tuesday's tantalising showdown at Old Trafford.
Cancelo fast joining the elite
Joao Cancelo is improving rapidly in Turin and produced another hugely effective performance. It was his run and shot that led to Ronaldo's opener and he largely stuck to his task well down the right, even as several of his team-mates seemed to switch off.
Bonucci pays price for complacency
Leonardo Bonucci had not had a great deal of defending to do, but the Juve defence were punished for the bizarre moment when they expected the ball to run out of play in the build-up to Bessa's goal. The Italy centre-back has to take a sizeable portion of the blame, though, as he failed to react in time and could only stand and watch as Bessa ran behind him to meet Kouame's cross.
Key Opta stats:
- Juventus have scored more first-half goals than any other team during Serie A this season, while Genoa have conceded more than any other (11) in the same period.
- Genoa's starting 11 is their youngest in Serie A this season.
- Christian Kouame is the youngest player in Serie A this season to create more than two assists.
Juve will now head to the north west of England to prepare for that Champions League showdown with United at Old Trafford. They then travel to Empoli in Serie A next Saturday. Genoa have eight days to prepare for Udinese's visit to the Luigi Ferraris.
|Paris Saint-Germain 2018-19: Mbappe´s continued rise shows Neymar is now disposable|
|Fognini follows up Nadal win by clinching first Masters title|
|Paris Saint-Germain 2018-19: How dominant title win compares to previous QSI years|
|BREAKING NEWS: PSG retain Ligue 1 title thanks to Lille draw|
|Everton 4 Manchester United 0: Toffees score biggest Premier League win over sorry Red Devils|
|Warner and Bairstow dominate again as Sunrisers thrash KKR|
|Colts owner Jim Irsay buys John Lennon´s ´Sgt. Pepper´ piano|
|People are having a free shot - Seibold defends young Broncos|
|Zidane must make Real Madrid hungry again - Seedorf|
|Young dropped as Solskjaer makes three changes for Everton clash|
|Lemar hopeful Griezmann stays at Atletico|
|Khan refutes Crawford´s accusations of quitting after low blow|
|Deciding doubles triumph sends Australia into Fed Cup final|
|Pakistan call up Yasir with Shadab laid low by virus|
|Wellington Phoenix 3 Melbourne City 2: Krishna´s last-gasp hat-trick boosts top-four hopes|
|Oh, for real? I didn´t know! - Harden unaware of early shooting woes|
|Solskjaer warns Alexis Sanchez Man Utd won´t carry players|
|Dele Alli thinks Tottenham´s Champions League run has Russian roots|
|Leilua brace downs Broncos as Raiders keep pace at NRL summit|
|Spalletti hails Inter´s Roma draw as ´precious´|
|Stuttgart had to make Weinzierl decision - Hitzlsperger|
|Tucker´s homer on MLB debut powers Pirates to fifth straight win|
|76ers win thriller, Rockets overcome Harden struggles to move 3-0 ahead|
|Crawford retains title by TKO after low blow stops Khan|
|MLS Review: De Boer´s Atlanta woes continue, Nani lifts Orlando|
|Garcia beats Granados via seventh-round TKO|
|Muller: Bayern feeling title pressure|
|He parks the bus right in front of De Gea – Van Gaal critical of Solskjaer again|
|Red Sox star Eovaldi on injured list with elbow issue|
|We real cool – Lillard plays down Westbrook feud|
|Embiid trolls Warriors after 76ers take 3-1 lead over Nets|
|Allegri dismisses criticism after Scudetto success|
|Solskjaer warns of no quick-fix for Man United in transfer market|
|Klopp a hermit amid Liverpool title hype|
|Dudley is ´a nobody´ – 76ers star Embiid|
|Johnson leads RBC Heritage heading into final round|
|Pogba can´t always have things his own way, says Solskjaer|
|Whyte to face unbeaten Rivas in July|
|Clermont hold off Harlequins to reach Challenge Cup final|
|Barcelona have to suffer to win – Valverde|
|Allegri staying at Juventus and targeting improvement|
|Man United win made Sociedad tough, says Barca´s Jordi Alba|
|Nadal: I probably played one of the worst matches on clay in 14 years|
|Sarri: Chelsea´s League Cup run on par with Tottenham´s heroics|
|Barcelona 2 Real Sociedad 1: Lenglet and Alba bring title closer|
|Inter 1 Roma 1: Perisic answers El Shaarawy stunner|
|La Rochelle edge past Sale to book Challenge Cup final berth|
|Capitals enjoy home comforts again to reign over Kings XI|
|Ronaldo proud of first Serie A season as Juventus celebrate title triumph|
|Ronaldo confirms Juventus stay after Serie A success|
|He´s showing great commitment - Gracia hails match-winner Deulofeu|
|Parker and Fulham ´discussing plans´ for next season|
|Juventus 2018-19: Ronaldo´s goals key to eighth successive Scudetto|
|I´m thankful that I´m playing for them - Vunipola grateful for support at Saracens|
|Newcastle United 3 Southampton 1: Perez hat-trick all but seals safety|
|Juventus 2018-19: Bianconeri join Europe´s fastest title triumphs|
|That point could make the difference - Ryan salutes resolute Brighton|
|Atletico Madrid defender Gimenez dislocates toe in Eibar win|
|Kovac: Patience key to crucial Bayern victory|
|Juventus 2018-19: How the Old Lady won an eighth straight Serie A title|
|Juventus 2018-19: The AC Milan team last to rule before the Bianconeri´s dominance|
|Juventus 2 Fiorentina 1: Bianconeri bounce back to seal Scudetto|
|Juventus seal eighth successive Serie A title|
|Pellegrini blames officials for more dropped West Ham points|
|Valencia appears to confirm Manchester United exit in Instagram post|
|Brumbies hold firm to see off Stormers|
|Halep on form but France draw level in Fed Cup semi|
|Pochettino refuses to criticise officials after missing out on penalty|
|Farrell guides Saracens into Champions Cup final|
|Eibar 0 Atletico Madrid 1: Lemar strikes late at Ipurua|