ROME — After becoming the most expensive transfer in Italian football history, Gonzalo Higuain quickly showed his value by coming off the bench to score the winner in Juventus' 2-1 victory over Fiorentina on the opening day of Serie A.

Higuain, who came up from Napoli in a 90-million euro ($99-million) deal, scored from a tight angle after a shot from Sami Khedira was deflected — eight minutes and 26 seconds after he came on and with just his third touch.

Earlier Saturday, substitute Diego Perotti converted two penalties before setting up another goal as likely title-challenger Roma produced a second-half outburst to beat visiting Udinese 4-0 in the Italian league opener.

In Turin, Khedira had put Juventus ahead with a header from the centre of the area midway through the first half, meeting a cross from Giorgio Chiellini.

Fiorentina was unable to produce a single shot in the first half but Nikola Kalinic equalized in the 70th with a header following a corner.

Five minutes later, Higuain was celebrating and the Juventus Stadium was rocking in welcoming its new star.

Fans had started cheering the moment Higuain got off the bench to warm up.

"They made me feel their affection from the first moment," Higuain said. "Hopefully I can repay this affection with goals and victories."

Higuain scored 36 times for Napoli last season to break a 66-year-old Serie A record for goals scored in a single season.

Higuain raised some doubts when he showed up overweight at his opening training session with Juventus, which was likely why he didn't start.

"I'm always confident, I just had to work," he said.

Former Barcelona winger Dani Alves also impressed in his Juventus debut.

Having also signed crafty playmaker Miralem Pjanic from Roma, expert defender Medhi Benatia from Bayern Munich and prized winger Marco Pjaca from Dinamo Zagreb, Juventus has assembled a squad that is expected to contend for the Champions League title.

Few observers expect Juventus to be challenged in Serie A, where it is attempting to win a record sixth consecutive title.

"We want to win all the titles possible this year," Higuain said. "But there's a long way to go. We're only at the start."

Since Serie A was founded in 1929, no club has won more than five straight tittles.

Torino won five consecutive titles from 1943-49 (including a season that was cancelled due to World War II), Inter Milan took five straight from 2006-10 and Juventus claimed a handful from 1931-35 before its current streak.

It was also a perfect start for Roma as the Giallorossi prepare for the return leg of the Champions League playoffs on Tuesday against Porto, following a 1-1 opening leg.

"It was really important to win and start well so we can approach the Porto match serenely," Perotti said.

Perotti's first spot kick came in the 65th after Edin Dzeko used a sharp change of direction to make defender Danilo fall on top of him.

Perotti played a part in drawing the second penalty, sending a through ball to Mohammed Salah, who sped past the defence, prompting Emmanuel Badu to tug him over.

Dzeko made it 3-0 from close range with his ninth Serie A goal in the 82nd and Salah finished things off two minutes later after taking a long pass from Perotti.

Roma has finished in the top three positions of the Italian league each of the last three seasons and is looking to take home a trophy this campaign.

Since joining Roma midway through last season, Perotti has scored five goals and provided seven assists in 16 Serie A appearances. More is expected of the Argentine this season after Pjanic's departure.

Rested at the start with the Porto match in mind, Perotti replaced Stephan El Shaarawy early in the second half.

"I feel great with Roma. I feel the confidence of my teammates and the entire club," Perotti said. "I'm always thinking about helping the squad, even off of the bench."

Captain Francesco Totti, beginning his 25th season with Roma, never left the bench — and fellow Giallorossi stalwart Daniele De Rossi also did not play.

Salah and Dzeko produced several early chances before a sparse crowd at the Stadio Olimpico.

Dzeko had a tough time settling in at Roma last season after a prolific spell at Manchester City but he made a big impact in this match, touching the ball 10 times in the opposition's box, more than any other player.

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Andrew Dampf on Twitter: www.twitter.com/asdampf