Earlier, Bologna were held to a 1-1 draw by lowly Serie B club Vicenza, while a dour clash between under-strength Piacenza and Chievo Verona sides ended in the same scoreline.
Despite resting a number of first-team regulars, including strikers Alessandro Del Piero and Marco Di Vaio, Juventus could still count on quality in every area of the pitch with Chilean Salas starting the game with last season's top scorer David Trezeguet of France, back from a knee injury.
A deadlocked first half gave way to a more open second half in which the home side threatened to go ahead when a clever move left striker Gianluca Savoldi one-on-one with Juventus goalkeeper Antonio Chimenti.
Savoldi shot wide but in the 67th minute the Serie A champions went ahead. Reggina midfielder Giandomenico Mesto clumsily brought down Juventus winger Gianluca Zambrotta in the area, and Salas calmly despatched the resulting penalty.
PUSH FORWARD
That proved the cue for the visitors to push forward and Salas's substitute, Zalayeta, volleyed home Juventus's second goal from close range a minute from the end of normal time.
Bologna dominated the first half of their match and missed taking the lead only because of poor close-range
Vicenza looked more determined after the break, but in the 57th minute Bellucci stunned the home side with a powerful right-footed drive that deflected off defender Alessandro Dal Canto into the goal.
Twelve minutes later, however, Vicenza substitute striker Stefan Schwoch restored parity after nodding a cross past Bologna goalkeeper Ferdinando Coppola.
The home side pushed forward in the final minutes of the game, but were unable to find the winner, allowing Bologna to take a valuable away goal to the second leg.
The earlier game between Piacenza and Chievo was played at a slower pace as both sides rested key players. Piacenza were without striker Dario Hubner, while Chievo rested midfielder Eugenio Corini and striker Massimo Marrazzina.
After a sluggish first half, Piacenza took the lead in the 59th minute when defender Vittorio Tosto volleyed a loose ball from 20 metres to beat Chievo goalkeeper Marco Ambrosio at his left-hand post.
Their lead did not last long. In the 65th minute, Chievo coach Luigi Del Neri brought on 18-year-old Brazilian striker Ariel Marcos de Paula and two minutes later he equalised, sweeping home the ball from close range after Sergio Pellissier's shot was blocked on the line.
