Brazil star Neymar will make his World Cup bow on Sunday as the five-time champions kick off quest for redemption while holders Germany launch their bid for back-to-back titles.
Four years after injury cut short his World Cup, before Brazil suffered a humiliating 7-1 semi-final defeat to Germany, Neymar is once again spearheading his country's hopes.
The Paris Saint-Germain striker's participation at the finals in Russia had been cast into doubt after he suffered a fractured right foot in late February.
However the 26-year-old forward has shown little signs of rust since returning for Brazil, scoring in consecutive friendlies on the eve of the finals.
That could spell trouble for Switzerland as they take on Brazil in Group E on Sunday.
Brazil coach Tite, who masterminded a dominant qualifying campaign which saw the "Selecao" finish 10 points clear of their rivals, said Neymar was "not 100 percent".
"But he has exceptional physical qualities, his speed in particular. In any case, he is in a suitable state to play," Tite said.
Neymar is the focal point of one of the most menacing attacks in the tournament, and could line up in a front four which includes Gabriel Jesus, Philippe Coutinho and Willian.
Switzerland meanwhile have regularly shown they are capable of punching above their weight, having only narrowly missed out on automatic qualification to Russia on goal difference behind Portugal.
Since securing their place via the playoffs, they have held Spain to a 1-1 draw and thrashed World Cup debutants Panama 6-0 in friendlies.
The Swiss also have pedigree in opening World Cup games, beating eventual champions Spain in their opener of the 2010 World Cup.
Brazil meet Switzerland in the newly-built 45,000 Rostov Arena in Sunday's evening game but before that Germany play Mexico in a mouth-watering tie in Moscow's Luzhniki Stadium.
Germany breezed through qualifying scoring 43 goals and conceding just four and, astonishingly, average almost four goals a game in their opening World Cup matches since last losing their first tournament game in 1982 against Algeria.
Coach Joachim Loew has, like the Brazilians, transformed the team from 2014 to the extent that the man who scored the World Cup winning goal in Rio, Mario Goetze, is not in the squad.
A young German side last year won the Confederations Cup in Russia, thumping Mexico 4-1 along the way.
Mexico though only lost one game in qualifying and have always qualified for at least the second round of every World Cup they have played. They have not beaten Germany though in three attempts at various World cups.
Germany are attempting to become only the third side in the World Cup's 88-year history to successfully defend their title, after Italy (1934-1938) and Brazil (1958-1962).
The magnitude of that task is not lost on Loew.
"It's the most difficult feat and history has demonstrated that, no one in 60 years has done it," Loew said on Saturday.
"Teams develop and change, players finish their careers and you must bring in new players which makes it the most difficult achievement."
Sunday's first game sees the 2014 World Cup's most surprising team Costa Rica take on Serbia in Samara.
The Central Americans topped a group including Uruguay, Italy and England last time to reach the quarter-finals, and this time are in Brazil's group.
Their pedigree may be good but their form is not and they have lost to Belgium and England in the run-up to Russia.
For Serbia, this year's tournament marks their first World Cup appearance since 2010 and are in good spirits having warmed up with a 5-1 win over Bolivia.
