The title credentials of champions Juventus come under fresh scrutiny in the 'Derby d'Italia' when a win for Inter Milan could see Roberto Mancini's men underline their scudetto hopes by seizing the Serie A lead.

Massimiliano Allegri's Juventus are well on their way to qualifying for the knockout stages of the Champions League, but it has been a bumpier ride on the domestic front.

A remarkably difficult start to the campaign has seen Juventus slump 10 points adrift of leaders Fiorentina and eight behind second-placed Inter.

Inter have not beaten Juventus at the San Siro since their treble-winning season of 2010, when they won league, Cup and Champions League under the helm of Jose Mourinho.

But an Inter win this time would leave Juventus 11 points adrift of the Nerazzurri, possibly too much, says Juve defender Andrea Barzagli, for the Turin giants to maintain hopes of a fourth consecutive scudetto.

"It's still early in the season but if Inter go 11 points ahead, it becomes problematic for us," said Barzagli.

He would do well to keep a close eye on Inter striker Mauro Icardi, who has hit six goals against Juventus in five games, three of which came while playing for former club Sampdoria.

Inter's only shock of the season was a 4-1 defeat by Fiorentina, the thrashing serving as a painful reminder to Mancini's men not to take their promising start for granted.

But Inter are back to full strength and welcome forward Stevan Jovetic back to the fold after a recent spell on the sidelines ended the on-loan Manchester City man's sterling start to the campaign.

Juventus will be missing Uruguayan defender Martin Caceres, who has a sprained ankle and will be sidelined "for 10-15 days", according to the club.

Caceres had been expected to play a role following his recent suspension for crashing his Ferrari while over the legal alcohol limit, but he hobbled off 18 minutes into a World Cup qualifying win over Colombia following a tackle by Juve teammate Juan Cuadrado.

Napoli and Fiorentina have joined Roma and Inter in throwing down the gauntlet and the credentials of both could become clearer when they kick off in the pick of Sunday afternoon's fixtures.

Fiorentina's unassuming start under new coach Paulo Sousa has been ultimately promising but Napoli, league runners-up in 2013, are beginning to purr.

Napoli's 4-0 away rout of AC Milan a fortnight ago came with a brace from Lorenzo Insigne and, after he missed Italy's Euro 2016 qualifiers with a sore knee, the little winger is expected to return to the fold.

It will be Napoli's first home game since their San Siro feat, but winger Elsed Hysaj said they won't be taking Fiorentina lightly.

"Fiorentina aren't top of the league for nothing, but we're coming off a really good run of games and we're determined to keep that going," said the Albanian international.

The pressure is firmly on Rossoneri coach Sinisa Mihajlovic, and although the Serbian has the full backing of Milan, drastic improvements are expected.

On-loan Liverpool striker Mario Balotelli, who has been sidelined with a muscle injury, is expected to start on the bench, if at all, for the trip to on-form Torino on Saturday.

Torino sit in fifth place, only five points behind Fiorentina, and Granata striker Maxi Lopez insists there will be little respect for the seven-time European champions.

"Milan have their history, but we deserve every point we've earned so far and it's possible we'll end up fighting for a top finish this season," he said.

Elsewhere, fourth-placed Roma can close their four-point deficit with a home win over Empoli on Saturday while city rivals Lazio, in third at three points off the pace, are away to Sassuolo.

Fixtures (times GMT)

Saturday

Roma v Empoli (1600), Torino v AC Milan

Sunday

Bologna v Palermo (1030), Napoli v Fiorentina, Atalanta v Carpi, Verona v Udinese, Genoa v Chievo, Sassuolo v Lazio, Frosinone v Sampdoria (all 1300), Inter Milan v Juventus (1845)
Source: AFP