MILAN, Aug 25 (Reuters) - A David Trezeguet hat-trick and two goals from Vincenzo Iaquinta gave Juventus a 5-1 home win over Livorno on their return to Serie A on Saturday. France striker Trezeguet put Juve ahead after half an hour when he headed in Alessandro Del Piero's cross from close range having earlier fluffed a glorious chance following Pavel Nedved's neat pass. Juventus, back in the top flight after their demotion last year for match-fixing, extended their lead midway through the second half when substitute Iaquinta converted a penalty after he was hauled down by defender Alessandro Grandoni. Italy striker Iaquinta, a close season buy from Udinese, claimed a second late on when Nedved's rasping shot deflected off him before Trezeguet grabbed his second and then a third with a backheel almost on the goal-line. Massimo Loviso scored a consolation for the visitors in injury time with a drive from distance. Lazio and Torino earlier drew 2-2 with the rest of the first round of matches taking place on Sunday.