Crespo sidestepped French defender Philippe Mexes before firing an unstoppable finish past goalkeeper Alexander Doni.

Zlatan Ibrahimovic failed to double the lead after the break from the spot as his low shot was blocked by Doni.

French midfielder Patrick Vieira was sent-off in the dying seconds after collecting a second yellow card.

The victory placed Inter third on seven points from three games while the Italian capital side are one spot behind with six points.

Elsewhere, Milan registered their first point of the season when they edged Ascoli 1-0.

Marek Jankulovski scored the winner eight minutes after the hour mark with a brilliant header.

Despite winning three games out of three, Milan just overcame the eight-point penalty that was handed after being found guilty in the sporting fraud scandal in Italy.

Carlo Ancelotti's side moved up to 12th spot.

In Cicely, Palermo crushed Catania 5-3 in the first derby of the city in 46 years.

Giovanni Tedesco, Fabio Simplicio, Amauri, Andrea Barzagli and Giuseppe Mascara scored for Palermo while Giorgio Corona, Eugenio Corini and Gionatha Spinesi.

Palermo are in charge of the Serie A table with nine points and Catania remain ninth on four.