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.
|Athletics´ Chapman undergoes procedure on left shoulder|
|Marcelo: Real Madrid miss Ronaldo|
|Ronaldo right about Juventus team spirit – Allegri|
|Klopp: I´m not the pope of football tactics|
|Stade beat Ospreys on emotional Chauvin tribute night|
|Ligue 1 survival bid a marathon not a sprint for Monaco, as club appoints distance runner|
|Vertonghen eyeing Spurs future beyond 2020|
|De Bruyne injuries could be a blessing for City, says Guardiola|
|Emery prepared to face Arsenal´s centre-back crisis|
|Ulster complete Scarlets double, Exeter gain Gloucester revenge|
|Sheffield United 1 West Brom 2: Baggies comeback boosts automatic promotion push|
|Del Potro back on court following knee injury|
|Canelo v Fielding: Rocky ready to write his own fairytale in New York|
|Boca part company with Schelotto after Copa Libertadores loss to River|
|Canelo v Fielding: Tale of the tape|
|Juventus defender Cancelo has knee surgery|
|Canelo v Fielding: Alvarez and Rocky make weight in New York|
|Spalletti does not fear another mid-season crisis at Inter|
|Salah headlines CAF Player of the Year shortlist as Koulibaly misses out|
|Beckham Jr. out of Titans clash|
|Lipsky hits the front at Leopard Creek|
|Pederson coy over Wentz back injury|
|Liverpool ´not really likely´ to be active in January window, reveals Klopp|
|Always on the move and unpredictable - Pavard reveals surprising choice over toughest opponent|
|We need to get back to respect - Lampard alarmed by hate in football|
|Giles returns to England to replace Strauss as director|
|Hansen has no issue with Milner-Skudder Toulon switch|
|Juventus to rest Ronaldo after Torino showdown|
|Titmus strikes gold again as world records tumble in Hangzhou|
|Malinga to captain Sri Lanka in New Zealand|
|Rivaldo would like ´excellent´ Isco at Barcelona|
|United a long way from Mourinho´s vision|
|´Klopp denies an answer!´ - Liverpool boss dismisses questions about ´world-class´ Pogba|
|Returning Nowitzki ´so tired´ after making NBA history|
|Aguero and De Bruyne in contention for Manchester City v Everton|
|Simeone has no plans to cash in on Costa|
|Canelo v Fielding: Alvarez´s greatest nights|
|Fabregas: Chelsea being unfairly scapegoated over racism allegations|
|Crisis? What crisis? Klopp focuses on defensive solutions for United clash|
|Hope cannot inspire Windies as Bangladesh cruise to series win|
|Benitez picks up Premier League Manager of the Month award|
|Chavez, Marquez and Canelo - Mexico´s greatest multi-weight world champions|
|Bale set to miss Real Madrid v Rayo Vallecano|
|Robben out until January as Bayern look to avoid serious injury|
|Milan avoid UEFA ban in FFP punishments.|
|Mourinho compares Liverpool to ´an amazing house´ but insists trophies matter|
|Brisbane Roar 2 Melbourne Victory 4: Muscat´s men hit A-League summit|
|Bumrah confident second Test is ´in the balance´ after India recovery|
|Isco gesture was for a corner or foul, claims Solari|
|Harris leads Australia into ascendancy on day one|
|ATP announces candidates to host future Finals|
|Ronaldo: Juventus fans refuse to lose to Torino|
|Hero Rivers feared he had cost Chargers in KC|
|Williams would welcome Llorente back to Athletic Bilbao|
|Liverpool v Manchester United: Minding the gap|
|Milan elimination unjust, fumes Leonardo|
|Paul hails ´sick´ Harden after record-breaking display|
|Liverpool v Manchester United: Salah, Mane and Firmino v Rashford, Martial and Lukaku in Opta number|
|Canelo open to GGG trilogy as he chases place in Mexican history|
|The big Friday Premier League quiz|
|Harden posts record fourth 50-point triple-double in win over Lakers|
|Barcelona squad happy with Dembele, says Alba|
|Chargers rally past Chiefs to clinch playoff spot|
|WATCH: Chargers top Chiefs on dramatic two-point conversion in final seconds|
|Suns owner Sarver committed to keeping team in Phoenix|
|Chargers WR Allen leaves with injury after near-spectacular catch|
|Socceroos not giving up on Mooy for Asian Cup|
|Cooper says Raiders owner wanted to trade him to Cowboys|
|Pochettino jokes Levy is ´worried´ about losing him|
|Barcelona would welcome Morata – Alba|