2018 World Cup: Previewing everything from Messi and Ronaldo to the best teams and matches

Five star players, five title contenders and five must-watch group stage games at the World Cup in Russia.

Of course the list starts here. The best player in the world has just one hole in his unparalleled resume: a title with his country. If he wins the World Cup, he rises to arguably the best of all time. Yet he almost didn't get here in the first place. Argentina struggled through qualifying, and needed a Messi hat trick in the last game to reach Russia. Can he work another miracle this summer?

To call him Messi's eternal foil is an understatement. They aren't just on opposite sides of the Barcelona-Real Madrid rivalry. Messi is small of stature, and often of ego. Ronaldo is tall and sculpted, from his hair to his self confidence. (He also has a title with Portugal, the 2016 European championship). Many fans love him, and many loathe him. But no one can ignore him.

No number in world soccer is more sacred than Brazil's No. 10. It's been Neymar's for a while, and it's been a burden at times. It likely was four years ago, when Brazil hosted the World Cup. He has grown up since then, and led the Seleçao to Olympic gold on home turf two years ago. Now he returns to the biggest stage of all.

A cult hero from Liverpool to Cairo, he's racing to be fit after injuring a shoulder in last month's Champions League final. Salah was the Premier League's top scorer this past season. He's also beloved in Rome, where he played before then. And of course, he's beloved in his country. Salah scored the penalty kick that sent Egypt to this World Cup, its first since 1990. Few players from any team will draw louder cheers in Russia.

He's the biggest star on a Mexican squad full of them. "El Tri" has reached the round of 16 at six straight World Cups, but hasn't made the quarterfinals since the '86 Cup on home soil. The so-called "fifth game" goal has become almost mythical. If Mexico is to get there, the striker known as "Chicharito" must deliver when it counts.

The five-time World Cup champions aren't on this list just because of their history. Or because of their star-studded squad, featuring playmakers Neymar and Philippe Coutinho, and towering defender Marcelo. It's because they won South America's World Cup qualifying marathon by 10 points, with a plus-30 goal difference. That's the strongest proof that Brazil is good enough for a sixth title.

Looking for a dark horse? This might be it. The winner of Group D — likely to be Croatia or Argentina — will have a favorable knockout-round path. Croatia is led by midfield conductors Ivan Rakitic and Luka Modric and striker Mario Mandzukic. Nicknamed the "Blazers," these men have more than enough talent for a deep run.

Twenty years ago, Les Bleus won their first World Cup, and took the world on a joyride. This year's squad has the potential to do it again. Paul Pogba, Antoine Griezmann and 19-year-old phenom Kylian Mbappé are just the start of what France will turn loose on the field. Their group should be easy, and the knockout round road looks favorable too.

There hasn't been a back-to-back World Cup winner since 1962. Germany might end that drought. The Mannschaft has built another machine, with a strong defense led by Mats Hummels and Joshua Kimmich. Julian Draxler is a midfield engine, and Thomas Muller will aim to add to his 10 career World Cup goals.

The 2010 champions have a new era of creators, led by Isco and Marco Asensio, and a stud goalkeeper in David de Gea. There's also just the right amount of veteran savvy: defenders Sergio Ramos and Gerard Piqué, and beloved midfield metronome Andrés Iniesta. A title, or at least a deep run, would send Iniesta out on the right note.

Friday, 2 p.m. (Fox, Telemundo)

One of the World Cup's most-anticipated clashes comes on the second day of the tournament. It's a battle of Iberian neighbors, and also a battle of club teammates. Five players on Spain's team play their club soccer for Real Madrid, alongside Portugal star Cristiano Ronaldo.

Saturday, 9 a.m. (Fox, Telemundo)

Two years after a legendary run at the European Championships, Iceland brings its Cinderella story to soccer's biggest stage. It's the nation's first ever World Cup, and it starts with as big a game as there is. Can Iceland upset mighty Argentina? Or will Lionel Messi silence the Viking Clap with thunder of his own?

Sunday, 8 a.m. (Fox, Telemundo)

Mexico has the hype, the United States has the angst, and Costa Rica has the track record. The Ticos reached the World Cup quarterfinals four years ago, and it wasn't a fluke. If they're to make another run this year, this game will be key. Goalkeeper Keylor Navas and big defender Kendall Waston must keep Serbian midfielders Nemanja Matic and Adem Ljaic quiet.

Sunday, 11 a.m. (Fox Sports 1, Telemundo)

Here's another glamorous early matchup with major implications. When these teams met in last year's Confederations Cup, Germany delivered a 4-1 rout. They're the clear favorite again this time. But Mexico will be spoiling for a fight, and has a potential star in attacker Hirving "Chucky" Lozano.

June 28, 2 p.m. (Fox, Telemundo)

After decades of disappointment, England's Lions aren't roaring too loudly these days. Most of their players aren't big names. Those who are could shine bright, such as Harry Kane and Dele Alli. Belgium, meanwhile, has many stars — and many play in the Premier League, led by Kevin De Bruyne and Eden Hazard. But the Red Devils have had chemistry problems in recent years. Will they solve them this time?