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.
|Durant says Green altercation won´t impact his free agency|
|Morris blasts drama surrounding Wizards: It´s messed up|
|Scaloni thrilled for Dybala, Icardi|
|Green´s last-second shot keeps Raptors atop East standings|
|Deschamps praises Griezmann for Giroud gesture|
|Warriors star Curry improving, still out at least three more games|
|Chile 4 Honduras 1: Sanchez, Vidal shine for La Roja|
|Argentina 2 Mexico 0: Icardi, Dybala score first international goals|
|Mickelson calls Tiger the greatest of all time|
|Durant fined $25,000 for using inappropriate language|
|Fizdale isn´t concerned about Knicks´ losing streak|
|No particular concern for Mbappe – Deschamps|
|PSG team-mate Choupo-Moting hopes Neymar injury is not serious|
|McLeish marvels at stylish Scotland´s promotion success|
|Draw proves Poland can play well without Lewandowski – Brzeczek|
|Giggs: Wales let themselves down|
|Sarachan ´moved USA forward´ in interim spell|
|Mickelson lays $200,000 bet with Woods for first hole|
|Dolphins QB Tannehill to start against Colts|
|Murcia edge out Banvit, Bonn crush Opava|
|Neymar injury not serious, says doctor|
|Mancini: Italy ahead of schedule|
|France 1 Uruguay 0: Giroud hits the spot after Mbappe injury blow|
|Portugal 1 Poland 1: Milik penalty salvages precious point as Danilo sees red|
|Italy 1 United States 0: Politano snatches late winner for Mancini´s men|
|Scotland 3 Israel 2: Forrest hat-trick seals Nations League promotion|
|Brazil 1 Cameroon 0: Richarlison fills Neymar´s boots as skipper suffers injury|
|France & PSG star Mbappe suffers shoulder injury|
|Albania 1 Wales 0: Gunter´s night spoiled by Balaj|
|Leeds and Manchester United to meet in friendly|
|Outspoken Smith leaves Cavaliers|
|PSG star Neymar injured for Brazil|
|Juventus midfielder Can back in training after surgery|
|Rams-Chiefs rollercoaster was the NFL´s modern-day masterpiece|
|Ronaldo an AC Milan target in 2017, confirms Fassone|
|Farah could get back on track at Tokyo Olympics|
|PSG still waiting on Alves and Kurzawa|
|Atalanta reject Gasperini to AC Milan speculation|
|Edmonton Oilers name Hitchcock new head coach|
|JR Smith on Cleveland Cavaliers: Tanking ´was always the plan´|
|Chester signs new Wakefield deal|
|F1 Raceweek: Countdown on to Alonso farewell|
|Rain disrupts Lorenzo´s Honda debut|
|VAR a possibility for Champions League knockout rounds|
|FFP vulnerable in areas, says UEFA president Ceferin|
|Sri Lanka draft in uncapped Peiris to replace Dananjaya|
|Coman back in Bayern training but Lewandowski has knee injury|
|Qalandars land De Villiers in PSL draft, Smith second pick|
|F1 changes helped less talented drivers on the grid - Alonso|
|Agnelli: No super league talks since 2015|
|I hope from now on it only gets better - Floersch update on horror crash|
|Calf injury rules Ashton out of Australia match|
|Halfpenny to miss South Africa clash|
|Hard for Lazio to hold on to Milinkovic-Savic, says Lotito|
|Australia´s next generation pay tribute to retiring Cahill|
|Bairstow pushing hard for Test recall|
|Cane eyes 2019 Super Rugby return after neck break|
|Van Dijk finds time to console referee during Dutch delight|
|Cahill sheds tear at end of phenomenal Australia career|
|WATCH: Pelicans coach Gentry interviews himself|
|Where does Chiefs-Rams classic rank among NFL´s highest-scoring matches?|
|Australia 3 Lebanon 0: Boyle bags brace on Cahill farewell|
|Guendouzi underlines desire to represent France|
|I might need a couple of drinks to relax after that! - Rams coach McVay|
|Juventus´ Alex Sandro has Premier League ambition|
|Ederson taking goalkeeping to another level, says City hero Weaver|
|Ceferin dismisses "super league" plans as fiction|
|Rams defeat Chiefs in one of the highest scoring games in NFL history|
|Kemba Walker leads Hornets to win over Celtics|
|Gomez praises ´top player´ Van Dijk, Stones|