This season's Serie A title race is shaping up to be the most interesting in years and it took another turn on Sunday when Juventus fell to a surprise 3-2 defeat at Sampdoria.
Inter Milan beat Atalanta 2-0 in the evening match to go second, two points ahead of six-time defending champion Juventus. Napoli, which beat AC Milan 2-1 Saturday, is top with 35 points to Inter's 33. Fourth-place Roma has 30 points with a game in hand.
Duvan Zapata, Lucas Torreira and Gian Marco Ferrari put Sampdoria 3-0 up in the second half before Juventus threatened an astonishing stoppage-time comeback with a penalty from Gonzalo Higuain and a strike from Paulo Dybala.
It will be a blow to Juve's confidence ahead of Wednesday's Champions League match against Barcelona.
"Explaining this match is difficult, it's a match which leaves you with your mouth open because we didn't let them have almost any chances," said Juventus coach Massimiliano Allegri. "We played very well in the first half but if we didn't score it means we weren't good in finishing. Then we conceded a goal on their first chance, that's also football."
It was Marco Giampaolo's first victory over Juventus as a coach.
"I'm very happy and I thank these lads for having given me this immense joy," he said. "After 10 years I've finally beaten Juventus, I hope I won't have to wait another 10 to beat it again."
Juventus was without defender Andrea Barzagli and goalkeeper Gianluigi Buffon, who were recovering from the disappointment of Italy's failure to qualify for the World Cup and Sampdoria made the most of their absences to expose the Bianconeri defensively.
Samp broke the deadlock six minutes into the second half when a poor clearance by Federico Bernardeschi on Fabio Quagliarella's cross fell straight to Zapata, who sent a looping header past Wojciech Szczesny.
Juventus upped the pressure but was stifled by a solid Sampdoria side, which doubled its lead in the 71st with a fine strike from Torreira from just outside the area into the bottom left corner.
It got worse for Juve eight minutes later. The defense should have dealt with a cut-back from former Juventus forward Quagliarella but Ferrari beat Sami Khedira to tap in from close range.
Juventus had penalty appeals turned down at the end of the first half but it was awarded a spot kick at the end of the second when Douglas Costa was tripped by Ivan Strinic for a last-gasp penalty. Higuain converted in the first minute of stoppage time but it seemed to be too little, too late.
Dybala reduced the deficit still further moments later when he ran down the right flank before cutting inside and placing the ball into the bottom right corner. But Juventus didn't have time to get the equalizer, with Higuain flagged offside in the last sequence of action.
Sampdoria is sixth with 26 points, two points behind Lazio. Both have a game in hand.
ICARDI AT THE DOUBLE
Two headers from Mauro Icardi sent Inter into second spot in Serie A after beating Atalanta 2-0.
Icardi missed a couple of opportunities before opening the scoring in the 51st after he was left unmarked to head in Antonio Candreva's free kick.
The Inter captain doubled his tally on the hour with a stooping header into the bottom left corner from Danilo D'Ambrosio's cross.
Benevento again came agonizingly close to claiming its first Serie A point, before a late goal saw it lose 2-1 at home to Sassuolo.
Samuel Armenteros netted in the 65th for Benevento to cancel out Alessandro Matri's opener but the hosts' hopes of getting something from the match were dashed when defender Gaetano Letizia was sent off two minutes later following a second booking.
Benevento clung on and it appeared as if its luck was about to change when Domenico Berardi hit the crossbar with a stoppage-time penalty but Federico Peluso netted the winner two minutes later.
Benevento has no points from its first 13 Serie A matches and has twice before conceded a stoppage-time winner.
Talented youngster Federico Chiesa celebrated signing a new deal at Fiorentina with a late goal to help it draw 1-1 at Spal.
Chievo Verona also drew 1-1 at Torino, where home striker Andrea Belotti had his penalty saved.
Elsewhere, new Genoa coach Davide Ballardini had an ideal debut as he steered his side to a 1-0 win at Crotone. Cagliari won 1-0 at Udinese.