Alessandro Del Piero scored twice - a cheeky back-heel and a penalty - and Emerson grabbed the other goal as Juve defeated lowly Siena 3-0, while Kaka netted a 74th minute winner for title-holders AC Milan in their scrappy 1-0 win against local rivals Inter Milan at the San Siro.

The Brazilian midfielder reacted quickly to redirect Gennaro Gattuso's low drive, which Inter keeper Francesco Toldo had covered, for his fifth league goal of the season.

Juve and AC Milan have 57 points from their 26 matches played, 13 more than third-placed Sampdoria who won 1-0 at Brescia on Saturday.

Defeat for Inter, their first in the league this season, left them in fourth place on 43 points.

Juventus coach Fabio Capello was delighted to see his team react positively after their 1-0 Champions League defeat away to Real Madrid on Tuesday.

"We are now confident of our potential once again," he said. "I always knew wed recover from that moment of nervousness. The team played with great determination and moved the ball around much faster."

AC Milan's match-winner Kaka admitted his team were lucky to claim all three points.

"It was a lucky moment for Milan, an opportunist's goal," he said.

Palermo improved their chances of qualifying for next season's Champions League with a hard-fought 2-0 victory over Roma, courtesy of second-half goals from Marco Brienza and Luca Toni.

The Sicilians' eighth home victory left them in sixth place, level on 42 points with Udinese who drew 2-2 at Fiorentina on Saturday.

Bottom club Atalanta, who already look doomed, came from behind three times to earn a 3-3 draw away to Cagliari, while Lazio eased their relegation fears with a 2-0 home win against strugglers Parma.

In other matches, Lecce and Reggina both sneaked 1-0 wins at home to Messina and Chievo respectively and Livorno drew 0-0 away to Bologna.

In Turin, Juve's Czech midfielder Pavel Nedved was ruled out after being knocked unconscious in Madrid, while French striker David Trezeguet failed to recover from the virus that forced him to miss the game in Spain.

Manuele Blasi came in for Nedved and Uruguayan forward Marcelo Zalayeta replaced Trezeguet.

Juventus dominated the early exchanges at the Delle Alpi stadium with Del Piero at the heart of every attack, but Siena always looked dangerous on the counter-attack.

After Tore Andre Flo and Rodrigo Taddei had gone close for the visitors, Juventus broke the deadlock with a lightning break.

Zalayeta slipped the ball through the legs of Francesco Colonnese wide on the right before crossing from the byline for Del Peiro, whose flick flashed past Alex Manninger in the Siena goal.

The visitors fell further behind soon after the break when Emerson rose to head home Mauro Camoranesi's right-wing corner and Del Piero completed the scoring from the spot in the 63rd minute after Emerson was brought down in the box.

The Milan derby was a rather drab affair and rarely lived up to its billing.

The best moment of the first half came in stoppage time when Inter's Juan Sebastian Veron's vicious drive was superbly turned away by Nelson Dida.

The decisive goal, which arrived 16 minutes from time, was a little harsh on Inter. Clarence Seedorf's left-wing corner was headed out by Ivan Cordoba, but only as far as Gattuso whose shot from the edge of the box was turned in by the instinctive Kaka.