Updated
Joe Hart endured a miserable debut as Torino were beaten 2-1 at Atalanta.
Iago Falque had put Torino into a 54th-minute lead with a free-kick which sailed past the seemingly unsighted Atalanta goalkeeper Marco Sportiello.
But barely a minute later the England goalkeeper, who moved to Italy on transfer deadline day after losing his place at Manchester City, gifted Andrea Masiello an equaliser.
Hart came off his line to clear a corner only to misjudge the flight of the ball, overstretch and leave Masiello with a tap-in from six yards.
He had the chance to make amends eight minutes from full-time after Atalanta were awarded a penalty, but Franck Kessie sent him the wrong way from the spot.
Milan's tough start to the season continued as they crashed to a 1-0 defeat at home to Udinese thanks to a late goal from Stipe Perica.
The Croatian striker lashed in the winner with two minutes left from Emmanuel Badu's cross.
There was still time for Carlos Bacca to salvage a point but his close-range header in stoppage time was saved by Orestis Karnezis.
Simone Verdi's first goal for Bologna helped secure a 2-1 win over 10-man Cagliari.
The 24-year-old striker, a summer signing from Milan, opened his account with a 25-yard free-kick midway through the first half.
Cagliari keeper Marco Storari was sent off nine minutes after the interval for handling outside the area as Ladislav Krejci raced through on goal.
Federico Di Francesco added the second in the 74th minute when he tapped in a cross from Krejci, before Bruno Alves pulled one back with a free-kick seven minutes from the end for the Sardinians.
Stefan de Vrij earned Lazio a point from a 1-1 draw away to Chievo.
Alessandro Gamberini headed the hosts into a 51st-minute lead from a corner, but three minutes later De Vrij nodded in Keita's cross to equalise.
Genoa's match with Fiorentina was abandoned after 28 minutes, with the score goalless, due to a hailstorm.
Mauro Icardi's stoppage-time strike earned Frank de Boer his first win as Inter Milan boss and sank newly-promoted Serie A side Pescara 2-1.
Inter, without a win since De Boer replaced Roberto Mancini two weeks before the start of the season, were trailing to Jean-Christophe Bahebeck's second-half goal before Icardi's late double rescued the Dutchman.
Substitute Bahebeck gave Massimo Oddo's side a 63rd-minute lead, but Icardi headed a 77th-minute equaliser and then fired the winner in the first minute of time added on.