Mauro Icardi scores goals. The Argentinian striker, who turned 25 in February, is a goalscoring machine. He's twice been top scorer in Serie A, including this season in which his 29 goals in 34 games—and his record for having the best conversion rate in Europe's top five leagues, according to WhoScored.com—helped fire his club Inter Milan into next season's UEFA Champions League for the first time since 2012.

At his current rate of scoring—and if Inter Milan can fend off advances from Chelsea for his signature, as reported by Cadena Ser and Il Messaggero (h/t TalkSport)—Icardi is going to surpass compatriots Gabriel Batistuta and Hernan Crespo as the leading Argentinian scorer in the history of Serie A. So why isn't he part of Argentina's 23-man squad for the FIFA World Cup finals in Russia?

"It's a big sadness that the great goalscorer of Italian football will not be in the World Cup," Matias Bustos Milla, a journalist with Argentinian newspaper Clarin, told B/R. "The case of Icardi is curious. For several years, Argentinian football fans have been asking about the big jewel: Why was he not been selected in the national team? There have been various trainers who didn't invite him onto their squads—Alejandro Sabella, Tata Martino, Edgardo Bauza."

This time it has been the turn of Jorge Sampaoli, who initially included Icardi in his preliminary 35-man squad for the tournament, to discard him. Sampaoli's squad is top heavy with centre-forwards; Manchester City's Kun Aguero and Gonzalo Higuain from Juventus have been chosen ahead of Icardi. The Inter Icardi has also missed chances to shine.

Sampaoli called up Icardi for crucial FIFA World Cup qualifying games last year. In three matches, including two starts against Venezuela and Uruguay, Icardi failed to score. "Higuain is criticised in Argentina for his scoring record so when Icardi arrived—playing in his position—he got his opportunity," says Pablo Lisotto, a journalist with Argentinian newspaper La Nacion, "but Icardi, in the few chances he got, he couldn't score goals either."

The reasons why Icardi has been left out in the cold are not all football-related, though.

"Icardi was 22 years old when he was made captain of Inter," says Milan-based David Schiavone, editor of Forza Italian Football. "It shows you the standing Inter have him at—to hand him the captaincy at such a young age. He enjoys being the target of fans' ire. He's the guy opposition fans will go after, and he's had two or three run-ins with Inter's 'ultras' before. He's a prickly guy. If he doesn't get on with people he's not one to shy away from confrontation."

It's unusual for a longstanding club captain to be so unpopular with his own hardcore group of fans. In a league game against Cagliari in October 2016, Inter's fans cheered when he missed a penalty. After a 3-1 defeat to Sassuolo in February 2015, an Inter ultra threw Icardi's jersey back at him after he tried to give it to a young fan, sparking a row between the player and fans, per Icardi's autobiography, Always Ahead: My Secret Story (h/t the Guardian).

Icardi wrote with schoolyard bravado about how he was oblivious to alleged fears from the club's directors for his personal safety in case some ultras surfaced at his house looking for retribution, maintaining he grew up in one of South America's toughest neighbourhoods. "How many of them are there?" he wrote. "Fifty? One hundred? Two hundred? OK. Record my message and let them hear it. I will bring 100 criminals from Argentina who will kill them on the spot." Inter's most passionate fans responded to the claims made in the book by issuing a statement, dismissing Icardi as a "clown," per BBC.

Icardi's love life also has all the ingredients of a telenovela, the name given to mawkish South American TV soap operas. He is married to Wanda Nara, an Argentinian TV celebrity and the ex-wife of Icardi's former team-mate at Sampdoria, Maxi Lopez.

In November 2013, Lopez and Nara ended a five-year marriage, according to a statement she released on Twitter (h/t La Gazetta dello Sport); a few days later, Icardi and Nara exchanged messages on Twitter—one of several social media forums in which they publicise their lives—with the hashtag #Quindicina, apparently a reference to the 15 times they had sex during a marathon 28-hour tryst in Argentina, per speculation on Ciudad Magazine, an Argentinian television station.

In May 2014, Icardi married Nara. According to Icardi's autobiography, she began flirting with him while she was still married to Lopez, inviting Icardi, for example, to cruise on a yacht with herself, Lopez and another Argentinian player, Gonzalo Bergessio, and his wife to the Aeolian Islands in September 2013.

Nara maintains her love affair with Icardi didn't begin, however, until after her divorce. In her divorce case—in which magistrates ruled in her favour—she accused Lopez of having several extra-marital affairs, including having sex with their au pair, Marianna, while Nara slept in another room with their children, per Chi, a weekly Italian gossip magazine (h/t La Gazetta dello Sport).

In April 2014, a month before Icardi's marriage to Nara, Icardi faced off against Lopez in a Sampdoria vs. Inter Milan Serie A game, which was dubbed "the Wanda derby." In the run-up to the match, Lopez complained in a television interview with Sky Sport (h/t Goal) about Icardi's habit of using Lopez's three sons as part of his social media offerings: "I can understand that, being a public figure, he publishes photos, but I'm not comfortable with my kids being in those photos."

Icardi responded by criticising Lopez on Twitter for being an absent father who neglects to visit his kids, and a few hours later posted a photo of himself dozing while cuddling one of Lopez's sleeping sons. In "the Wanda derby" four days later, Lopez refused to shake Icardi's hand before the game.

Inter Milan won 4-0. Icardi scored twice; Lopez missed a penalty. Two months later Icardi got a tattoo of the three sons' names on his arm, which he unveiled in a tweeted photograph, MailOnline.

Icardi—who now has two daughters with Nara—has become notorious for his role in the love triangle. His name has become a byword for marital treachery in Argentina. "When [the marriage broke up] most people were angry with Icardi. They sided with Maxi Lopez," says Bustos Milla. "But Icardi and Nara have stayed together so people have come to understand that human relationships work that way. But in the world of football, Icardi is still marked with that scandal. Actually, in Argentina, what Icardi did became a verb. When there is a betrayal between friends and a lover, it's called 'icardiar'—it means 'to steal the girlfriend of a friend.' It was a complicated situation at the beginning."

Diego Maradona has branded Icardi "a traitor," and when former Argentina national coach Tata Martino was asked to explain why he had omitted Icardi from his Copa America squad in May 2016, he put it in moral terms: "Regarding the subject of Icardi, we all know what is right and what is wrong," per Telam news agency (h/t ESPN FC).

Lopez denied that Messi—who he played alongside at Barcelona early in the latter's career—and Javier Mascherano, who won a league title with Lopez at River Plate in 2004, vetoed Icardi's inclusion in national team squads, per Radio La Red (h/t Goal).

Football coaches have emotional intelligence, however. Icardi's bullish personality—which is played out on social media channels with a wife who acts as his agent and has had a chequered, much-publicised sex life—is different to the low-key social lives of Messi and Mascherano.

"Some people say that Messi and Icardi don't have a good relationship, and that Icardi's high profile in social media and Instagram is [annoying], but this is only conjecture. There is no evidence that Icardi isn't going to the World Cup because of Messi," says Lisotto. It could be unsettling, though, to have Icardi in camp for the long, idle weeks of a World Cup tournament. The world may well have to wait until Qatar in 2022 to see him shine in the competition.

"A lot of people in Argentina think Icardi should be in the team instead of Higuain," says Bustos Milla. "These people don't love Icardi or think he is the best but they definitely prefer him over Higuain. There is debate. But without a doubt Icardi should be the next No. 9 of the national team after this World Cup. He is the future.

"We have this idea about Icardi—that he is a rebel. Like Maradona or Che Guevara, he's a guy who doesn't obey any rules, but this is exactly what makes them strong. Probably if Icardi respected rules he wouldn't be the player he is. Like a Mario Balotelli or a Zlatan Ibrahimovic, guys who are rebels with big egos and strong personalities. For Argentinians, we don't like rebels at the beginning, but by the end they conquer us. We end up seduced by them. We like rebels like Icardi in the end."

Follow Richard on Twitter: @Richard_Fitz