Ronaldo shoulders Portuguese hopes
Portugal will be appearing at their eighth World Cup and sixth in a row. Their best performance was on their debut in 1966 when they finished third after losing to England in the semi-finals and they reached the semi-finals in 2006 before losing to France. They went out in the group stage in 2002 and 2014 and lost to Spain in the round of 16 in 2010.
Coach: Fernando Santos
Key players:
Cristiano Ronaldo: Portugal's captain, most capped player and all-time leading scorer remains, at the age of 33, a fundamental presence for Portugal -- even when not playing, as he showed by encouraging the team from the touchline during the Euro 2016 final.
Some feel his habit of hogging free kicks and penalties is not healthy and that his presence is a burden for his team mates, but his record of 81 goals in 149 games speaks for itself.
Pepe: The linchpin of the defence for the best part of a decade although his rash tackles, explosive fits of temper and liberal use of gamesmanship make him many people's pantomime villain.
He let down the team when he was sent off in the first half of the 4-0 defeat by Germany in the 2014 World Cup but held the back line together magnificently in the Euro 2016 final against France. Born in Brazil and moved to Portugal as an 18-year-old.
William Carvalho: Known as "Sir William" by fans of his club Sporting, Carvalho was born in Angola and moved to Portugal as a child.
Physically imposing, he forms a defensive wall in front of the Portugal defence and is remarkably calm in possession, providing excellent distribution, though he sometimes looks cumbersome and slow.
Form guide:
Portugal have won their last nine competitive internationals although their form in friendlies since qualifying has been more erratic, with two wins, a draw and an embarrassing 3-0 defeat by the Netherlands.
Prospects:
Along with neighbours Spain, Portugal appear to be favourites to progress from Group B which also contains Morocco and Iran. But facing Spain in their opener could complicate things as defeat would leave them playing catch-up. Their second match against Morocco will stir unhappy memories of a 3-1 defeat by the North Africans at the 1986 finals while the Iran match brings them face to face with their former coach Carlos Queiroz. Russia, Egypt, Uruguay or Saudi Arabia await in the second round while France and Argentina are among possible quarter-final opponents.
African Champs Morocco face tough challenge
Morocco are appearing in their fifth World Cup finals, but their first since the 1998 edition in France. They were only the second African country to play at the finals, picking up a first point at the 1970 tournament in Mexico and then in 1986 becoming the first African country to get past the opening round when they topped a group ahead of England, Poland and Portugal. They were narrowly beaten by West Germany in the last 16.
Coach: Herve Renard
Key players:
Younes Belhanda: A graduate of Montpellier's prodigious youth system, the crafty midfielder helped the unfashionable club to win their first Ligue 1 title in 2012 and was named France's best footballer at the same time. The success led to a lucrative move to Dynamo Kiev, where he slipped somewhat from view, but he went to Galatasaray on a four-year deal last July and the 28-year-old is again proving his worth.
Mehdi Benatia: French-born centre-back whose career looked stuck in Ligue 2 before he moved to Italy and made a quick impression with Udinese, his fortunes surging as he was signed by Roma, Bayern Munich and then Juventus. The 31-year-old won two Bundesliga titles at Bayern and now two in a row with Juventus.
Karim El Ahmadi: The 33-year-old defensive midfielder is likely to call time on his international career at the end of the World Cup. He captained Feyenoord to their first league title in 18 years last season and at the end of the year was voted best player in the Dutch league.
Form guide:
Morocco beat Serbia and Uzbekistan in warm-up friendlies in March and their home-based national team, made up of players from their local league, won the African Nations Championship which the country hosted in January.
Prospects:
Morocco have been handed a tough draw after being grouped with Portugal, Spain and Iran. They must get their Group B campaign off to a winning start against Iran on June 15 in St Petersburg and then hope for results against the reigning European champions and 2010 World Cup winners.
Strong run in boosts Iran
Iran will be appearing at the World Cup finals for a fifth time, although qualification for Russia is the first time the country has booked a spot at successive tournaments having previously played in 1978, 1998, 2006 and 2014. The Iranians are still looking to progress to the knockout rounds for the first time and have won just one match, against the United States, in France in 1998.
Coach: Carlos Queiroz
Key players:
Sardar Azmoun: The heir-apparent to Iranian great Ali Daei, 23-year-old Azmoun has established himself as Iran's leading forward since breaking into the team in the lead-up to the 2015 Asian Cup finals. As comfortable in the air as he is on the ground, the Rubin Kazan forward carries a constant goal scoring threat.
Alireza Jahanbakhsh: Exciting winger Jahanbakhsh goes into his second World Cup finals off the back of a remarkable season in the Netherlands' Eredivisie, where he has been one of the standout players for AZ Alkmaar. Quick and skilful, Jahanbakhsh can play on either flank or behind the striker.
Saeid Ezatolahi: Ezatolahi has picked up the mantle of predecessors such as Karim Bagheri and Javad Nekounam as the man who makes Iran tick from central midfield. The 21-year-old's performances in front of the defence have been instrumental in the country's impressive form over the last three years.
Form guide:
Queiroz has regularly complained about the difficulties he has faced in preparing his team for the World Cup, in particular the domestic-based section of his squad, but Iran have recorded several solid results since qualifying. A draw with hosts Russia in Kazan was followed by wins over Venezuela, Sierra Leone and Algeria as well as a narrow loss against Tunisia.
Prospects:
Drawn in a challenging group with Morocco, Spain and Portugal, the Iranians will be looking to pick up a win in their opener against the Moroccans to ensure their quest for a first-ever place in the round of 16 stays alive until their final game, against the Portuguese. Well-drilled and growing in experience, Iran could spring a surprise against either Spain or Portugal if they gain that morale-boosting victory over Morocco.
Iniesta hopes last hurrah with Spain
Spain have played in 14 World Cups and qualified for every edition since 1978. They have won it once, beating the Netherlands 1-0 in the 2010 final in South Africa with an extra-time strike from Andres Iniesta.
Before then they had reached the quarter-finals in 1934, 1986, 1994 and 2002 but lost every time. As holders they suffered a shock elimination from the group stage in 2014.
Coach: Julen Lopetegui
Key players:
Isco: Lopetegui knows how to get the best out of the Real Madrid playmaker. He can play across midfield, behind the striker or even as a deep lying centre-forward and ran riot in impressive wins over Italy and Argentina.
Andres Iniesta: The Barcelona veteran has conducted Spain's all-powerful midfield for more than a decade and was the heartbeat of their world dominance between 2008 and 2012.
Still as masterful on the ball as ever at 34 years of age, he will be looking for one last hurrah in Russia before quitting international football.
Sergio Ramos: The centre back and captain has developed a win-at-all-costs mentality and knows exactly how to manage the biggest games. An unforgiving opponent for attackers due to his physical presence and never-say-die attitude, Ramos's experience of four Champions League finals with Real Madrid and five major tournaments will be vital to Spain's hopes.
Form guide:
Spain have not lost since their Euro 2016 last-16 defeat to Italy and have won 13 out of 18 games with Lopetegui, drawing five. They comprehensively beat France and Belgium in international friendlies and proved their credentials by ripping apart Argentina 6-1 in their last outing.
Prospects:
Spain will face a testing opener against European champions Portugal which is likely to determine whether they finish top of Group B, which also contains Iran and Morocco.
If they win the group they are likely to face either Uruguay or Egypt in the last 16, with a possible quarter-final against Argentina, Croatia or France coming next.
Given the talent in the squad and their form under Lopetegui, a semi-final appearance should be the minimal target, although they will feel confident they can go all the way.
