Neymar makes his World Cup bow on Sunday as five-time winners Brazil kick off their quest for redemption while defending champions Germany launch their bid for back-to-back titles.
Four years after injury cut short his World Cup and Brazil went on to suffer a humiliating 7-1 semi-final defeat to Germany without him, 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 broken bone in his right foot in late February.
However, the 26-year-old forward has shown few 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 that 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 that includes Gabriel Jesus, Philippe Coutinho and Willian.
Brazil meet Switzerland in the newly built 45,000 Rostov Arena in Sunday's evening game but before that Germany play Mexico in a mouthwatering tie in Moscow's Luzhniki Stadium, where they will be hoping to return for the final on July 15.
Germany breezed through qualifying, scoring 43 goals and conceding just four and, astonishingly, they 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 only lost one game in qualifying and have always reached at least the second round of every World Cup they have played. But they have not beaten Germany 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," he 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."
Mexico coach Juan Carlos Osorio pledged his team would go on the attack against the Germans, who he said were favourites to win the World Cup.
"Nevertheless, we can compete with them," he said. "We think we have a good chance to match up with them and go head to head against them."
Sunday's first game sees 2014 World Cup surprise package Costa Rica take on Serbia in Samara.
Away from the football, Russian authorities said a taxi driver who ploughed into pedestrians on a pavement near Red Square in Moscow on Saturday, injuring at least seven people, had been suffering from exhaustion.
The taxi driver, a 28-year-old man from the central Asian republic of Kyrgyzstan, told police during questioning that he had been working for 20 hours solid before the incident and had mixed up the brake pedal and the accelerator.
The driver said he ran from the scene because he feared he would be beaten to death.
The incident occurred about 200 metres (yards) from Red Square, which was packed with foreign football fans snapping pictures of the Kremlin on a warm and sunny afternoon.
And a space for gay and ethnic minority football fans in Saint Petersburg during the World Cup was forced to relocate at the last minute in a move activists believe was politically motivated.
Piara Powar, director of the international anti-discrimination network FARE, which is overseeing the project, said the move was "familiar" to rights groups.
British gay rights activist Peter Tatchell was briefly arrested last week for a one-man protest near Red Square against President Vladimir Putin's record on gay rights. Violence against gays in Russia regularly makes global headlines.