Serbia midfielder Dusan Tadic has backed fellow countryman Sergej Milinkovic-Savic to ignore the transfer rumours surrounding his signature and focus instead on his country's World Cup campaign.

Milinkovic-Savic and Tadic both featured in Serbia's opening 1-0 win over Costa Rica on Sunday, in which Aleksandar Kolarov scored the decisive goal.

Southampton man Tadic told FourFourTwo that his teammate needs to "keep calm" amid reports of the player being linked with the likes of Real Madrid and Manchester United.

"He is a good player, he is young. He can learn a lot of things but he has a big talent," Tadic said. "He has the capacity to go far. That's it. He is the future of Serbian football.

"I say to him to just be calm and work smart and he does. He needs to work for his team and then after he can show his qualities.

"I think he is a clever guy. He is a good boy and he just needs to keep his head calm [despite the rumours]. There is a big future for him."

Serbia top Group E after Brazil were held to a 1-1 draw by Switzerland.