Napoli handed Inter Milan its first loss in 26 Serie A games this season, getting a third-minute goal Sunday from Marcelo Zalayeta and pressing them for the remainder of the match.

Zalayeta lifted the ball over Julio Cesar when the Inter goalkeeper came outside of the area and failed to clear a long pass.

The defeat left Inter with 61 points, six better than AS Roma, which beat Parma 4-0 on Saturday. Juventus has 48 and Fiorentina 47.

“We are not playing so well right now so a loss like this can happen,” Inter coach Roberto Mancini said. “We still have a good margin so this shouldn’t demoralize us. Julio Cesar is always strong. Unfortunately tonight he made a mistake.”

Also Sunday, Pablo Osvaldo scored in injury time to lead fourth-place Fiorentina over third-place Juventus 3-2.

With the support of its home crowd at San Paolo stadium, Napoli pressed throughout and gave Inter few chances to equalize. Inter’s best opportunity came in the 19th when Napoli keeper Matteo Gianello saved a close-range shot from David Suazo.

With Napoli dominating the pace, Julio Cesar had to dive to stop a header from Napoli defender Paolo Cannavaro that was heading for the corner of the goal in the 29th.

Julio Cesar made several other key saves including a dramatic stop on an errant kick by Inter defender Marco Materazzi that almost resulted in an own-goal. The keeper also blocked a well-placed penalty kick by Zalayeta in the 75th.

“I take all the responsibility for the goal,” Julio Cesar said. “After I blocked the penalty I thought that might energize us. I told the guys, ‘Come on, get a goal for me.’ We have to remain with our heads high because we are still six points ahead.”

With strikers Zlatan Ibrahimovic and Julio Ricardo Cruz both unavailable, Mancini started Suazo and 18-year-old Mario Balotelli. Mancini replaced defender Christian Chivu - who injured his shoulder at the beginning of the second half - with striker Hernan Crespo in a failed bid to spark his offense.

The loss extended Inter’s winless streak in Serie A to three, after having won 18 of its first 23.