Inter, looking unstoppable when they won 3-1 at Juventus in early November, have since entered crisis mode after taking only one point in their last three games and are determined to stop the rot.
Italy under-21 international Perin, on loan from Genoa, has had a baptism of fire in Serie A with his side losing 6-1 to Juventus, 5-1 to Napoli and 4-1 to AC Milan.
Last week, however, the promoted side ended Fioretina's unbeaten home record with a 2-0 win which would not have been possible without Perin's heroics.
His 15 saves included a brilliant reflex dive to stop Alberto Aquilani's header and another to grab a curling free kick from the same player.
"It was an exceptional result, but we only stayed in the game because of Perin," said coach Cristiano Bergodi who replaced Giovanni Stroppa in November. "He's an interesting kid, who has great qualities and who could have a great career ahead of him."
However, Bergodi quickly tempered the praise with a warning.
"Mattia is a great goalkeeper but he is one of our youngsters and with players of this age it is not easy to escape relegation."
Perin, who was given his first senior callup by Italy for last August's friendly against England, even found himself refuting comparisons with Juventus and Italy goalkeeper Gianluigi Buffon.
"Don't exaggerate," he told Gazzetta dello Sport. "Goalkeepers such as Buffon are only born every 40 years. There are only 20 years between me and Gianluigi, which makes unlikely that I can reach his level."
Pescara have won three of their last four games, pulling four points clear of the relegation zone, while opponents Inter appear to be going in the other direction.
Only one point behind leaders Juventus at the start of November, Inter have now slipped to fifth and are nine points adrift of top spot after losing 3-0 at Udinese last Sunday.
"We faded towards the end of 2012 but there's still half the season to play," said captain Javier Zanetti. "We need show more belief than ever. We must bounce straight back."
However, Inter will be without three key defenders as Andrea Ranocchia and Juan Jesus are suspended and Walter Samuel has an achilles tendon problem.
Juventus, whose lead was cut to five points after their shock 2-1 home defeat to Sampdoria on Sunday, are away to Roberto Donadoni's Parma, who boast the only unbeaten home record in the league.
"It doesn't really matter what happened last Sunday against Sampdoria," said the former Italy coach.
"We have to be at our best whatever has happened. They are a great side."
Meanwhile, Juve coach Antonio Conte was delighted with the way his side bounced back to beat AC Milan in the Italian Cup on Wednesday.
"I received a great response from everyone including players who had not played for a while," he said.
Second-placed Lazio have what appears to be a straightforward home match against Atalanta, who are in the lower half of the table.