Opinion: Watch these soccer players in the World Cup — and how they cash in afterward

Belgium forward Eden Hazard could command one of the costliest transfer fees of the summer.

As the most-watched sporting event on the planet, the FIFA Men’s World Cup is an unequaled opportunity for the soccer players heading to Russia. If they play well, they can become icons.
Their performances can also have a significant impact on their professional careers, particularly for lesser-known players. The summer tournament overlaps with the height of the transfer market in professional soccer, during which players are bought and sold in a global market.
When one professional soccer team wants to acquire a player, it pays a transfer fee to the player’s current team. Players also negotiate a new, usually larger salary from their new team.
The first recorded transfer fee, paid in England in 1902, was only 1,000 pounds. By 1982, when Diego Maradona was recruited from Argentina to Barcelona after a brilliant performance in the World Cup, the transfer cost about $7.6 million — a new record. Two years later, after a troubled season, Barcelona sold him to Napoli, setting another record of about $10.5 million.
Today, those amounts would seem like a steal. Last year, Paris Saint-Germain paid $263 million to Barcelona to acquire the Brazilian superstar Neymar Jr., in addition to offering him a $53 million yearly salary.
That record probably won’t be broken this year. Even so, teams can make incredibly costly mistakes, paying out huge sums for players who flop on their new teams. As journalist Simon Kuper and economist Stephan Szymanski argue in “Soccernomics,” managers and teams often make really bad decisions surrounding transfers. Trades made on the basis of World Cup performances can often be unwise, with players who did well in the tournament overvalued on the market. After the 1998 World Cup, for instance, the Spanish club Real Betis paid about $35 million for the Brazilian player Denilson de Oliviera, then a new record. Denilson, a fantastic dribbler, shone on the Brazil team, but his career at Betis was mixed.
While the attention during the World Cup is usually focused on major stars, most of whom are already established in top clubs in Europe, most movement in the transfer market takes place at a much lower level.
The wealthiest teams are concentrated in Europe, with English, German, Italian and Spanish and Italian clubs at the center, the French league increasingly powerful, and clubs in countries like Belgium, Norway, and Switzerland much less prominent. But a move from Latin America or Africa to one of these smaller European leagues can be an important step for a player. And, increasingly, teams in China as well as the U.S. — despite salary cap rules in the M.L.S. — are able to pay enough to recruit young star players, the way Atlanta United FC did with an Argentine phenomenon named Ezequiel Barco, who at the age of 19 is making $1.4 million and was recruited with a $15 million transfer fee from his club.
As the plot of the World Cup unfolds, here are some teams to watch both for what they do at the tournament and where their players may end up afterward.

Belgium
When I put together my fantasy English Premier League team each fall, I just put as many Belgians as I can on the team, and I end up with a pretty amazing roster. Why are there so many great Belgian players?
In 2002, the Belgian Football Federation embarked on a far-reaching and successful reform of youth development in the country. And because Belgium is so marginal within the European soccer economy, professional teams can really only make money by selling players on the transfer market. It will probably help Belgium that many of its star players currently play together on their professional teams: Lukaku and Marouane Fellaini at Manchester United; Jan Vertonghen, Toby Alderweireld and Moussa Dembélé at Tottenham; and goalie Thibault Courtois and striker Eden Hazard at Chelsea.
Hazard has hinted he is not sure if he will stay at the club this summer. If he does move, it will likely be one of the most expensive transfers of the summer.

Colombia
At the 2014 World Cup, James Rodriguez scored what many considered the goal of the tournament — and was later chosen as the best goal of the year — in a game against rivals Uruguay. His performance in the tournament was followed by an $89 million transfer to powerhouse team Real Madrid, making him one of the most expensive players on the planet. He hasn’t thrived there, however, and spent the last year on loan to Bayern Munich. His World Cup performance could play a role in where he moves next.
This year’s World Cup squad is considered one of the teams to watch, with many star players, including goalkeeper David Ospina of Arsenal and Juan Cuadrado of Juventus. But watch for forward Miguel Borja, who recently moved to the Brazilian team Palmeiras for a $10.5 million transfer fee, one of the highest ever in the country. With a strong World Cup performance, he likely will be eyed by European clubs.

Egypt
Mohammed Salah has, through one incredible season at Liverpool, become one of the most beloved soccer stars on the planet. His injury during the Champions League final in May left fans of Egypt deeply worried, but he now seems healed enough to take up the helm of his team during a historic appearance. Egypt was one of the early members of FIFA, and the first African team to compete in the World Cup in 1934. But since then, the country has only been back once. Qualification this time was secured by Salah, and he is the clear leader of the team.
Egypt goes to the World Cup with a roster made up almost entire of professionals who play at home (one exception is defender Omar Gaber, on the roster of Los Angeles F.C.). For many of them, especially given the political and economic difficulties surrounding Egyptian soccer, the World Cup represents a major opportunity to attract the attention of foreign teams. Playing alongside Salah, the striker Marwan Mohsen could gain the attention of European teams if he plays a good tournament.

France
Like Belgium, France has put a lot of state investment into its soccer development. Its national training academy, Clairefontaine, was established in 1988 and is a model worldwide. Kylian Mbappé, the 19-year-old star striker on the team, grew up in the Paris suburb of Bondy and was trained at Clairefontaine.
A few decades ago, France was like Belgium in that it exported most of its major players, and the stars of the 1990s generation spent most of their careers abroad. Now, though, foreign money has poured into the top French league. Paris Saint-Germain, bankrolled by Qatari investors, has become a major player in European soccer. Mbappé plays at Paris Saint-Germain with Neymar, and a good number of other players on the French team are based in the country professionally.
N’Golo Kante, a brilliant midfielder who until 2015 was playing in the lower divisions of French soccer before being recruited by Leicester City and then Chelsea, is rumored to be eyeing a move back home, to Paris Saint-Germain, in what would be an extremely expensive transfer.

Senegal
Senegal has only one major international star on the roster, Sadio Mané, who in 2016 was recruited to Liverpool for a $34 million transfer fee, the highest paid until then for an African player. Most of his teammates are far less well-known, so the tournament will be an important opportunity for them.
Eight of the Senegal players were born in France to Senegalese parents, and most played for France’s youth teams as teenagers. But since 2004, FIFA has allowed players who play for one country at the youth level to switch to another as an adult, as long as they decide to do so before they are 21.
For the players, such choices are complicated, and the professional stakes are high. Though the French team is more highly ranked, they might have a better chance of being selected for the World Cup if they chose to play for Senegal.
The forward Moussa Sow, for instance, was born in grew up on the outskirts of Paris, and played on the French U-19 team before opting for Senegal, has played in Turkey and the United Arab Emirates for the past years, but has been eyed by English clubs in the past. A strong tournament for him could open up new opportunities for him there, or back in France.

Laurent Dubois teaches the course Soccer Politics at Duke University and is the author of “The Language of the Game: How to Understand Soccer.” Follow him on Twitter @SoccerPolitics.