Italy is among the contenders at the rescheduled European Championship – delayed a year due to the coronavirus pandemic – as the 1968 winner prepares to face Turkey in the tournament's curtain-raiser in Rome on Friday.
A proud football country but a national team on its knees after failing to qualify for Russia 2018, its first World Cup absence since 1958, Mancini has overseen a drastic recovery following his appointment more than three years ago.
Banishing the nightmares of Gian Piero Ventura's dismal tenure, Italy are in the midst of a 27-game unbeaten streak – a run dating back to September 10, 2018. Heading into Euro 2020, Mancini's men have won eight successive games in all competitions without conceding a goal for the first time in their history.
Italy was one of only two teams – alongside Belgium – to win 100 per cent of their games during the Euro 2020 qualifying campaign (10/10). The Azzurri scored 37 goals in its 10 qualification matches (3.7 per game) – this was the same tally in qualification for Euro 2016 and the 2018 World Cup combined (37 goals in 22 games).
As Italy gears up for its Euro 2020 Group A opener at the Stadio Olimpico, where it has never lost in a major tournament – it has won six and drawn two in the World Cup and European Championship combined, having not conceded a goal in each of the last seven fixtures – Azzurri great hailed the impact of Mancini.
"Mancini is one of my best friends," former Inter, Milan and Juventus striker Vieri, who earned 49 caps for Italy from 1997 to 2005, said.
"He did an amazing, amazing job. Getting the Italian team back together and getting all the fans in Italy to watch again because no one was watching.
"They have big players, big quality players – real quality like what we used to have 10-15 years ago. We had a situation for 10-15 years after the 2006 World Cup, we didn't have any big players. That's how it is sometimes, you don't have big players coming up.
"Now we have big players, we have experienced players. They play fantastic football and haven't lost for so many games, but they are really, really strong."
This is Mancini's first major tournament as Italy head coach. As a player, he only featured at one major final: he played four games at Euro 88, scoring the opening goal of the whole tournament during a 1-1 draw with hosts West Germany.
Italy, who will also face Switzerland (June 16) and Wales (June 20) in Group A, are taking part in their 10th European Championship finals. They won the tournament in their first appearance (1968) and have since reached the final twice without lifting the Henri Delaunay trophy (2000 and 2012).
"I told him [Mancini] I don't know if you're going to win the Euros, but you're going to get there," added Vieri, who scored 23 goals for the national team. "The team is strong, and they have big players again and everyone is following."
Another former Italy international, Walter Zenga, also lauded Mancini's work at the helm of the four-time world champions, while highlighting the quality of the entire coaching staff that includes Gianluca Vialli and Daniele De Rossi.
A three-time winner of the IFFHS World's Best Goalkeeper award, ex-Inter star Zenga – regarded as one of the greatest keepers of all time – played 58 games for Italy between 1987 and 1992, including appearances at the World Cup in 1986 and 1990 and Euro 88.
"The important thing right now is we have a great coach. Not only a great coach but a great standard of staff," said Zenga, who still holds the record for going 518 minutes (five consecutive clean sheets) without conceding a goal at the 1990 World Cup.
"All the technical staff were involved in football – Vialli, De Rossi, et cetera. This helps the team to grow up and arrive at the Euros with a big chance to win."
A lot of attention will be on number one goalkeeper Gianluigi Donnarumma, who has played a key role amid Italy's undefeated streak under Mancini.
There is also uncertainty over Donnarumma's future, with the 22-year-old star out of contract at Milan and tipped to join Ligue 1 giants Paris Saint-Germain.
"You have to consider one nice thing in life and football: you can improve yourself every day," Zenga said when asked about the quality of Donnarumma, who debuted as a 16-year-old for Milan in 2015. "There's no one day that you say you're at the top level, especially when you're 22.
"I've met him a lot of times in Milan and his character is very strong. He is strong because either if he makes a big save, makes an unbelievable game or the worst game of his life, he looks like he is [in] complete control of himself. This is the most important thing in life. He is the top goalkeeper in Italy."