One thing to know: At 38 years old, Tim Cahill will be one of the oldest players in the tournament, and will be looking to score in his fourth consecutive World Cup.
(Photo by Robert Cianflone/Getty Images)
28. Saudi Arabia
Key players: Mohammad al-Sahlawi, Fahad al-Muwallad
First match: vs. Russia (June 14, 11 a.m. ET)
One thing to know: In 2002, Saudi Arabia failed to score a goal at the World Cup, losing all three of their matches and leaving the tournament without a highlight. Anything better than that would be a win this year.
(Photo by PAUL ELLIS / AFP)
Key players: Wahbi Khazri, Ferjani Sassi
First match: vs. England (June 18, 2 p.m. ET)
One thing to know: Tunisia qualified for the World Cup for the first time since 2006 this year, and will be seeking it's first World Cup win since 1978.
(Photo credit should read VALERY HACHE/AFP/Getty Images)
One thing to know: Japan was winless in Brazil four years ago, but have a puncher's chance to advance through to the knockout round this year thanks to a competitive group that could get messy.
(Photo by Masahiro Ura/Getty Images)
Key players: Gylfi Sigurdsson, Albert Gudmundsson
First match: vs. Argentina (June 16, 9 a.m. ET)
One thing to know: With a population just over 325,000, Iceland is the smallest country to ever qualify for the World Cup. It's roughly the equivalent of Pittsburgh, Pennsylvania making it to the final 32.
(Photo by Lynne Cameron/Getty Images)
Key players: Mikel John Obi, Alex Iwobi
First match: vs. Croatia (June 16, 3 p.m. ET)
One thing to know: Alex Iwobi may be the best kept secret of the World Cup this year, but if for no other reason, watch Nigeria for the fact that they have the best kits in the tournament by a long shot.
(Photo by Erwin Spek/Soccrates/Getty Images)
Key players: Marcus Berg, Andreas Granqvist, Emil Forsberg
First match: vs. South Korea (June 18, 8 a.m. ET)
One thing to know: Sweden's solid defending carried them to the World Cup, earning their spot over Italy after winning 1-0 on aggregate. It was the first time Italy failed to qualify since 1958.
(Photo by MICHAEL CAMPANELLA/Getty Images)
Key players: Sadio Mane, Moussa Konate
First match: vs. Poland (June 19, 11 a.m. ET)
One thing to know: Senegal is making just its second appearance ever at the World Cup. In their one previous trip to the tournament the country made it all the way to the quarterfinals before falling to Japan.
(Photo by VI Images via Getty Images)
Key players: Ayoub El Kaabi, Hakim Ziyech
First match: vs. Iran (June 15, 11 a.m. ET)
One thing to know: It's Morocco's first trip to the World Cup in 20 years, and they could be a threat to make the kncokout stage. While Portugal and Spain are heavily favored to escape the group, a big win over Iran to open the tournament could prove vital down the line.
(Photo credit FADEL SENNA/AFP/Getty Images)
Key players: Mohamed Salah, Ahmed Hegazi
First match: vs. Uruguay (June 15, 8 a.m. ET)
One thing to know: Mohamed Salah scored five of the team's eight goals in qualifying, and will have to keep an impressive offensive pace if Egypt is to advance past the group stage.
(Photo by Khaled DESOUKI / AFP)
Key players: Fyodor Smolov, Anton Miranchuk, Aleksei Miranchuk
First match: vs. Saudi Arabia (June 14, 11 a.m. ET)
One thing to know: Russia hasn't won a match at the World Cup since 2002. The home team's best shot at victory will be come against Saudi Arabia to open the tournament.
(Photo by Anton Novoderezhkin\TASS via Getty Images)
18. Costa Rica
Key players: Bryan Ruiz, Marco Ureña
First match: vs. Serbia (June 17, 8 a.m. ET)
One thing to know: Costa Rica's run in the 2014 was unforgettable, with the team somehow winning one of the "groups of death" that consisted of Uruguay, England and Italy. Will they capture a similar magic this year?
(Photo by JOHN THYS / AFP)
Key players: Nemanja Matic, Aleksandar Mitrovic
First match: vs. Costa Rica (June 17, 8 a.m. ET)
One thing to know: Serbia is reponsible for one of the most impressive goals you'll see all year— featuring four passes without the ball touching the ground including a bicycle pass right before the finish. That was against Bolivia — can they do it against World Cup competition?
(Photo by Vitaly Nevar\TASS via Getty Images)
Key players: Robert Lewandowski, Jakub Blaszczykowski
First match: vs. Senegal (June 19, 11 a.m. ET)
One thing to know: Robert Lewandowski scored a whopping 16 goals for Poland out of the qualifying group — the next closest player in the stage was Denmark's Christian Eriksen with eight.
(Photo by Piotr Matusewicz/PressFocus/MB Media/Getty Images)
Key players: Christian Eriksen, Thomas Delaney
First match: vs. Peru (June 16, 12 p.m. ET)
One thing to know: Expect Denmark to essentially live and die by the play of Christian Eriksen, who will be leveling up from his role as creator at Tottenham to all-around showman for his country.
(Photo by Alex Grimm/Getty Images)
Key players: Mario Mandzukic, Luke Mondric, Ivan Rakitic
First match: vs. Nigeria (June 16, 3 p.m. ET)
One thing to know: Iceland and Croatia split their matches against each other while qualifying for the World Cup. Now paired together in the group stage, one more match between the teams could decide who moves onto the knockout round.
(Photo by GIUSEPPE CACACE / AFP)
Key players: Haris Seferovic, Granit Xhaka, Stephan Lichtsteiner
First match: vs. Brazil (June 17, 2 p.m. ET)
One thing to know: Brazil is a tough draw in your opening game of the World Cup — chances are you'll know a lot about Switzerland in their first few minutes on the pitch.
(Photo by TF-Images/Getty Images)
Key players: Paolo Guerrero, Alberto Rodríguez, Pedro Gallese
First match: vs. Denmark (June 16, 12 p.m. ET)
One thing to know: Peru was the final team to qualify for the World Cup and enters as one of the hottest teams in international play. It's their first trip to the tournament since 1982.
(Photo by Fabrice COFFRINI / AFP)
Key players: Javier Hernandez, Carlos Vela
First match: vs. Germany (June 17, 11 a.m. ET)
One thing to know: Mexico has been eliminated from six consecutive World Cups in the first match of the knockout stage. This could be the year they buck the trend — either with a trip to the quarterfinals or a disappointing finish in the group stage.
(Photo by Laurens Lindhout/Soccrates/Getty Images)
Key players: Radamel Falcao, James Rodriguez
First match: vs. Japan (June 19, 8 a.m. ET)
One thing to know: James Rodriguez won the Golden Boot in Brazil four years ago with an astonishing six goals in the tournament. A similar performance this year could help Colombia match their run to the quarterfinals.
(Photo by MARCO BERTORELLO / AFP)
Key players: Cristiano Ronaldo, Rui Patricio
First match: vs. Spain (June 15, 2 p.m. ET)
One thing to know: This will be the fourth trip to the World Cup for Cristiano Ronaldo. In each of his three previous trips, he's managed just one goal for his country. Turning his stellar offense on is likely the key to Portugal's potential this year.
(Photo by Sergei Savostyanov\TASS via Getty Images)
Key players: Harry Kane, Deli Alli, Raheem Sterling
First match: vs. Tunisia (June 18, 2 p.m. ET)
One thing to know: All 23 players on the England squad play in the Premier League. After disappointing finishes in the past few World Cups and an embarassing loss to Iceland at Euro 2016, there's plenty for this All-Star team to prove.
(Photo by Robbie Jay Barratt - AMA/Getty Images)
Key players: Luis Suarez, Diego Godin
First match: vs. Egypt (June 15, 8 a.m. ET)
One thing to know: Uruguay has won the World Cup twice, and with a favorable group stage schedule, could be poised to make another deep run this year.
(Photo by Miguel Rojo / AFP)
Key players: Lionel Messi, Sergio Aguero
First match: vs. Iceland (June 16, 9 a.m. ET)
One thing to know: While Messi is certainly the star of the show, Sergio Aguero may hold the key to Argentina's success. In two trips to the World Cup he's yet to score a goal.
(Photo by Gabriel Rossi/Getty Images)
Key players: Eden Hazard, Romelu Lukaku, Mousa Dembele
First match: vs. Panama (June 18, 11 a.m. ET)
One thing to know: Aside from England, Belgium brings the most Premier League players to the World Cup this year, with more than half the team playing their club ball in England's top flight.
(Photo by Peter Lous/Soccrates/Getty Images)
Key players: Olivier Giroud, Hugo Lloris, Paul Pogba, Kylian Mbappe
First match: vs. Australia (June 16, 6 a.m. ET)
One thing to know: Stacked with talent, France should be a force through the World Cup, but a baffling draw with the USMNT in the team's final tune-up will certainly have French fans concerned heading into their first match.
(Photo by GERARD JULIEN / AFP)
Key players: Diego Costa, David Silva, Andres Iniesta, Sergio Ramos
First match: vs. Portugal (June 15, 2 p.m. ET)
One thing to know: Spain might be the most complete team in the field, but after crashing out of the group stage in Brazil four years ago and a less-than-stellar showing at Euro 2016, La Roja are definitely out to prove themselves.
(Photo by Jose Breton/NurPhoto via Getty Images)
Key players: Neymar, Thiago Silva, Philippe Coutinho
First match: vs. Switzerland (June 17, 2 p.m. ET)
One thing to know: Brazil is playing for redemption this year after getting embarassed 7-1 in the 2014 semifinal against Germany. They could face the Germans again in either the first round of the knockout stage, or the final.
(Photo by Nelson ALMEIDA / AFP)
Key players: Mesut Ozil, Thomas Muller, Manuel Neuer
First match: vs. Mexico (June 17, 11 a.m. ET)
One thing to know: Should Germany go on to win the tournament this year, it'd be the first time a country has taken back-to-back World Cups since Brazil accomplished the feat it in 1958 and 1962.