Talk of crisis five games into the season may be premature but the pressure on Juventus and Roma to reveal their scudetto credentials is palpable amid Inter Milan's 100 percent start to Serie A.

Juventus finished last season with their fourth consecutive league trophy, the Italian Cup and a ticket to the Champions League final, where Massimiliano Allegri's men were humbled 3-1 by Barcelona.

But so far the Turin giants have a grand total of five points from one win, two draws and two defeats that have left them in 13th place 10 points adrift of leaders Inter.

Roma are faring only slightly better, Rudi Garcia's men -- who have finished runners-up the past two seasons -- in ninth place at seven points behind Roberto Mancini's pacesetters.

This time last year Juventus and Roma had already left many of their supposed title rivals behind.

Now, further slip-ups in their respective games away to Napoli and at home to Carpi could see the roles reversed.

"We have to improve quickly," admitted Allegri after the champions conceded a last-minute equaliser at home to Frosinone, allowing the league new boys to claim their first ever point in Serie A in midweek.

Roma were holding on for a deserved share of the spoils at Sampdoria on Wednesday before defender Kostas Manolas turned comically into his own net with five minutes left on the clock as the hosts ran out 2-1 winners.

"I'm satisfied with the way we played but we didn't deserve to lose this game," claimed Garcia.

Allegri will be without injured Mario Mandzukic for what already was a difficult encounter at Napoli, and faces a selection dilemma after being forced to change tactical formation halfway through Wednesday's draw in Turin.

He is now expected to partner Paulo Dybala with Alvaro Morata up front, with Gianluigi Buffon -- rested alongside Patrice Evra and other regulars -- returning between the posts to replace Norberto Neto.

Allegri has brushed off suggestions of a crisis, but warned his side: "We have to grow as a team by winning games, not by making costly mistakes.

"We need to work and improve to bring this squad up to a certain level. We have to improve, otherwise we'll become a team that can beat everybody but also be beaten by everybody."

The only positive for Juve is the unpredictable form of Napoli.

After failing to win their opening three games, Maurizio Sarri's men hammered Club Brugge 5-0 in the Europa League, and added another five goals in a stunning 5-0 home win over Lazio last Sunday.

On Wednesday, however, they were held to a scoreless draw at league newcomers Carpi, prompting media to suggest Napoli had run out of goals.

Sarri was unapologetic, saying: "People will call me crazy, but I think we played a good game."

Media pundits have gone into overdrive, with Mediaset claiming the loser at Napoli's San Paolo stadium on Saturday can kiss goodbye to the league title.

But Sarri added: "I don't really think that's the case."

On paper, Roma should claim an easy three points at the Stadio Olimpico but Carpi have held Palermo in Sicily and almost held Inter last month before Stevan Jovetic scored a late penalty to give the Nerazzurri a 2-1 win.

Inter, meanwhile, have won their opening five games for the first time in nearly 50 years -- although aficionados would underline the Nerazzurri finished runners-up, to Juventus, at the end of the 1966-67 season.

Mancini's leaders face arguably their toughest test so far when they host Fiorentina, who sit second at three points adrift, at the San Siro on Sunday.

Elsewhere, AC Milan travel to Genoa looking for their third consecutive win and Lazio visit Verona looking to capitalise on the absence of injury-hit striker Luca Toni.