Richarlison scored twice as tournament favourites Brazil beat Serbia 2-0 in their World Cup opener on Thursday, but the win was soured by an ankle injury to captain Neymar.

The record five-time winners had toiled at times in the first half but improved after the break at the Lusail Stadium and were rewarded when Tottenham Hotspur striker Richarlison followed in to score the opener in the 62nd minute after a Vinicius Junior shot was saved.

Vinicius then set up Richarlison to score again in the 73rd minute with a stunning acrobatic effort that is surely the goal of the World Cup so far.

However, Neymar was then forced off with a sprained ankle that the Brazilian team doctor said would be assessed over the next 48 hours.

Injuries have hampered Neymar at the tournament in the past and Brazil will hope his World Cup has not ended already, although coach Tite struck a positive tone after the game.

"You can be certain that Neymar is going to play in the World Cup," said Tite.

Thursday's result continues Brazil's superb record in the World Cup group stage, in which their last defeat came in 1998 against Norway.

Tite's side are now already on top of Group G ahead of Switzerland, who beat Cameroon 1-0 earlier and who Brazil meet next.

"We played well, especially in the second half when our opponents started to tire and we took advantage of that," said Richarlison, who called it "a boyhood dream come true" to score the goals.

The scoreline was the same as when these sides met in the group stage in 2018 but Brazil are determined to do far better than four years ago, when they lost to Belgium in the quarter-finals.

They have come to Qatar as the favourites for a sixth title, two decades after their last victory.

Other results in the opening round of matches in Qatar served as a warning, with Argentina suffering a shock defeat to Saudi Arabia at the same stadium and Germany losing to Japan.

Brazil would have known not to take Serbia lightly, but it still would have been a huge shock for them to lose at a ground where they intend to return for the final on December 18.

Serbia coach Dragan Stojkovic said his team "fell away physically" and added that injuries to key players, including Juventus duo Dusan Vlahovic and Filip Kostic, hindered his side.

"We came here with a lot of injuries to deal with affecting key players. That is the way it is and we have to face this fact," he said.

Tite sent out a very attack-minded side, with Neymar in support of Richarlison while Raphinha and Vinicius occupied the wings and Lucas Paqueta added creativity in midfield.

Serbia did their best to frustrate Neymar, who come close to scoring direct from an early corner that would have raised the roof at the magnificent Lusail Stadium, where the stands were filled with yellow and green.

The best Brazilian moments in the first half came when Thiago Silva's defence-splitting pass found Vinicius in the box, only for goalkeeper Vanja Milinkovic-Savic to thwart the Real Madrid man, and when Raphinha played a one-two with Paqueta before his shot was saved.

Barcelona winger Raphinha was involved again within a minute of the restart when he hounded Nemanja Gudelj out of possession but was again denied by the goalkeeper.

However, Serbia's resistance was broken just after the hour mark.

The warning had come when Alex Sandro lashed a left-foot shot off an upright and two minutes later the goal arrived.

Neymar set up Vinicius for a shot that Milinkovic-Savic got a hand to, but the ball broke to Richarlison who followed in to score.

Serbia responded by bringing on Vlahovic, but Brazil had now found their stride and the second goal when it came was worthy of the biggest stage.

A Vinicius cross with the outside of his right boot was controlled by Richarlison who then spun around and leapt to score with an outrageous acrobatic effort.

Brazil could have scored more, with Casemiro seeing a shot come back off the crossbar, but this was a promising start, as long as Neymar's injury is nothing serious. (AFP)