The head of the White House Task Force for the World Cup on Tuesday defended the decision not to grant visas to a Somali referee and some support staff for the Iranian team.

Serena Williams said she had "so much fun" as the American legend rolled back the years in her triumphant return to tennis in the Queen's Club doubles on Tuesday.

Somali referee Omar Artan said the "biggest dream of my life" had been ripped away after he was denied entry to the United States to officiate at the World Cup.

Five-time winners, Brazil needed a superb Vinicius Junior equaliser to draw 1-1 with Morocco in their opening game at the World Cup on Saturday as Australia conjured a stunning 2-0 upset of Turkey.

The United States emphatically launched its home World Cup Friday, thrashing Paraguay 4-1 with a perfectly scripted opening performance to delight a star-studded home crowd in Los Angeles.