Coach Giampiero Ventura says "it would be a catastrophe" if injury-hit Italy failed to qualify for the 2018 World Cup with key qualifiers looming against Macedonia and Albania.

Italy look set to go through the play-offs as they sit second in Group G behind Spain before Friday's clash against Macedonia in Turin followed by a trip to Albania three days later.

"I'd say it would be a catastrophe," Ventura told a press conference at the team's training camp at Coverciano outside Florence when asked about the possibility of missing out on the finals in Russia.

The four-time world champions need only a point from the two matches to secure second place in the group and a spot in the play-offs.

But the Azzurri could do with maximum points to boost their standing in the world rankings (they are currently 17th), and ensure they are seeded for the play-off draw next month.

"I'm not thinking about the play-offs, we need to think about the next two matches and then based on who we meet we'll weigh things up," said Ventura.

Ventura confirmed that Roma captain Daniele De Rossi was out against Macedonia with a knee injury with Inter Milan midfielder Roberto Gagliardini called up in his place.

Lorenzo Pellegrini, Marco Verratti and Andrea Belotti have already been sidelined with niggling problems.

Atalanta's Bryan Cristante, who nabbed the equaliser for a 2-2 draw against Juventus on Sunday, received his first call-up for the national team.

"These are things that happen," said Ventura.

"De Rossi is out and he will go (back to Roma) - besides him we will have to do without Pellegrini and Verratti too.

"All three will be missing, but whoever plays will hopefully prove themselves to be an important resource for the national team."

"We are still Italy and we have to improve on so many things," he continued.

"When we meet stronger teams we have to be well prepared, before the World Cup we will have so many training sessions, while now we have only 48 hours.

"Once we qualify we can do some experiments but for the moment it's not possible, we need certainties."

Italy face Macedonia on October 6 and then travel to Albania for an October 9 clash that will be the country's 800th international, and their first on Albanian soil.

Revised Italy squad:

Goalkeepers: Gianluigi Buffon (Juventus), Gianluigi Donnarumma (Milan), Mattia Perin (Genoa)

Defenders: Davide Astori (Fiorentina), Andrea Barzagli (Juventus), Leonardo Bonucci (AC Milan), Giorgio Chiellini (Juventus), Danilo D'Ambrosio (Inter Milan), Matteo Darmian (Manchester United/ENG), Daniele Rugani (Juventus), Leonardo Spinazzola (Atalanta), Davide Zappacosta (Chelsea/ENG)

Midfielders: Nicolo Barella (Cagliari), Bryan Cristante (Atalanta), Daniele De Rossi (Roma), Roberto Gagliardini (Inter), Marco Parolo (Lazio)

Forwards: Federico Bernardeschi (Juventus), Antonio Candreva (Inter), Stephan El Shaarawy (Roma), Lorenzo Insigne (Napoli), Simone Verdi (Bologna), Eder (Inter), Manolo Gabbiadini (Southampton), Ciro Immobile (Lazio), Roberto Inglese (Chievo)