Last summer, Casemiro helped Brazil to win their first Copa America trophy since 2007. He was due a break. A few weeks after the final, he was enjoying some rest with his family in Sao Paulo when his earth shook. It was a Saturday night. He watched on television as his Real Madrid club-mates took a beating from city rivals Atletico Madrid 7-3 in a pre-season tournament in New Jersey. What he saw made his eyes hurt. 

He was due to head to Orlando, Florida, with his mother, wife, their three-year-old daughter, and his sister. It was going be some precious family time, but now all bets were off. He cancelled his holiday. Disney World would have to wait. Instead, he jumped on a plane to Spain so he could report for training at Valdebebas, Real Madrid's training ground, on Monday morning. The following week, he put in a 45-minute shift against Red Bull Salzburg in another pre-season friendly. Real Madrid won 1-0. Order was being restored.

"What's special about Casemiro is the the way he stitches his team's play together," says Donato, who played as a defensive midfielder for Atletico Madrid and Deportivo La Coruna in the 1990s. "His reading of the game is excellent. He's one of those players who interprets well the flow of a game. He knows how to anticipate danger. He knows that it's important to defend for Real Madrid.

"He makes everything look easy. He does a lot of things people don't see, sniffing out danger before it happens. But what I love about Casemiro is that he's very mature. When Real Madrid needs him to do something more, he knows the moment to do it. He knows how to both organise his team's play and also when to arrive in the box—to score goals. He knows his function in the team.

"He has the humility to support those skilful, attacking players around him in midfield like Luka Modric, Toni Kroos and Isco, but he does what's necessary. When he appears in the box, it's because Real Madrid are not doing well so he pops up and he can score his golitos (little goals) and appear in the photo next day in the newspaper, like he did in the game against Sevilla when he scored two goals."

The weekend before last, Sevilla, who were fourth in the table and five points behind Real Madrid, paid a visit to the Bernabeu. It was a tight match. Casemiro put his side ahead in the second half with a lovely dink over the goalkeeper. Sevilla quickly equalised. Five minutes later, Casemiro headed in the match-winner for Real Madrid.

A lot is made of Casemiro's defensive abilities—he is a runaway leader in La Liga's charts for interceptions made—but he also has a killer instinct; his long-range effort in the 2017 UEFA Champions League final against Juventus to put Real Madrid on the road to victory, for example.

"He does what you want your defensive midfielder to do—he makes excellent tackles; his reading of the game has improved vastly; he's very strong, incredibly fit—and recently he's also started scoring goals," says Phil Kitromilides, TV presenter and a producer of The Spanish Football Podcast. "He's actually scored more goals in his Real Madrid career than Toni Kroos [and the same as Luka Modric]. There's a lot to his game."

Casemiro is a non-negotiable asset for Real Madrid head coach Zinedine Zidane, and his second-most-used player this season behind Karim Benzema. Since the sale of Marcos Llorente to Atletico Madrid during the summer, there is no direct replacement for Casemiro in Real Madrid's squad. Club president Florentino Perez has a meme saved on his phone in which three-quarters of the world is covered by water and the remaining quarter is covered by Casemiro.

Donato makes the point that when Brazil went crashing out of the last FIFA World Cup in the quarter-final stages, Casemiro was noticeably absent from their team through suspension. If he was playing, Belgium wouldn't have found it as easy to flood through Brazil's midfield en route to a 2-1 victory.

Casemiro had a tough start in life. When he was four years old, his father walked out. His mother had to clean houses to bring some money home while Casemiro looked out for his two younger siblings.

It wasn't until he was 14 years old and taken into residency by Sao Paulo as a youth team player that he began sleeping in the same room night after night—he'd been used to alternating between a bed in his house, his aunt's house, his grandparents' house or team-mates' houses. The hardscrabble upbringing has seemingly helped him, however.

"He comes from a country where he was used to it being competitive," says Brazilian-born Donato. "We are very competitive people. He put together what he has from his background with aspects from European football. I did the same myself with the tools I had. With everything I learned in Brazil, I adapted to Europe.

"As a defensive midfielder, we know very well our role. Casemiro has become very important to Real Madrid. There is a lot of competition inside the club— to play there year after year, as he has done, is not easy." 

Casemiro is a consummate professional. He uses a software platform called Wyscout to study opposition teams and players he will encounter. It's not just complete games he watches, but specific details. He likes to anticipate their movements, the positions they take up.

"Casemiro admits he doesn't have the most exquisite touch on the Real Madrid team, but he's improved a lot his precision and his judgement," says David Alvarez, a journalist with El Pais. "He uses analysis to better himself. He robs more balls. He commits less fouls, and he has more touches on the ball now than he had, say, three years ago."

For example, Casemiro told Libero magazine he used his advance analysis of Kylian Mbappe to help him steal the ball from the French star during the 2-2 draw between Real Madrid and Paris Saint-Germain in a UEFA Champions League game at the Bernabeu in November. And there's nothing Casemiro likes better than robbing the ball.

Casemiro's aptitude for learning and self-improvement is noteworthy. His attention to detail is legendary. He had a gym installed in his house, and he has his own physio. He has his siesta in a custom-built sleep chamber. When he's studying Mbappe and other opponents on video, he rests his legs in equipment designed to help recover the strength in his muscles.

"It's different to see a footballer from Brazil who is so 'European' in his mentality," says Alvarez. "He's very strict on himself. He is not the stereotypical, flamboyant Brazilian footballer. He's a very sober, serious guy. In a lot of aspects, his personality doesn't appear like that of a typical Brazilian footballer. Rodrygo has spoken about how Casemiro is always demanding more work, saying, 'Hey, Rodrygo, let's go to the gym' or 'Let's go to the physio.'"

The work has paid off. After a shaky start at Real Madrid—when he arrived in 2013 overweight for a reported fee of €6 million, and subsequently spent a season on loan at Porto—Casemiro has become irreplaceable, a lynchpin of the famous Real Madrid team which won three UEFA Champions League titles on the bounce from 2016 to 2018 and has designs on reclaiming their crown this season.

"He's still only 27. He has yet to reach his peak," says Kitromilides. "The Real Madrid fans love him. They realise that no else does what he does—he's vital for the team. He's like a machine. Every game, he runs, he makes the tackles, and that's what Real Madrid fans want to see. Almost as much as the flair, they want to see commitment from their players.

"When he made his Real Madrid debut against Real Betis in 2013, I wasn't hugely impressed. I wouldn't have thought he would go on to become a first-choice holding midfielder in the team and win several Champions League titles. It speaks a lot for him as a person, as a player—the way he has learned and developed. He bided his time until Zidane gave him his opportunity to establish himself. His trajectory—to go from Castilla [Real Madrid's reserve team] to captaining Brazil is quite a story."

Follow Richard on Twitter: @Richard_Fitz