LOS ANGELES -- Wherever possible, Manchester United have tried to keep Mason Greenwood under wraps. It is club policy that youth team players under the age of 18 are not allowed to speak to the media, and even official channels, in-house television station MUTV and the United website, are only rarely granted special access.

United have been especially careful with Greenwood, similar to the way Sir Alex Ferguson shielded Ryan Giggs nearly 30 years ago. The problem, though (if you can call it that) is Greenwood has done more than enough talking on the pitch. So much so, in fact, that Jose Mourinho has taken the 16-year-old to the United States for this summer's preseason tour. He's so young that club photographers are not allowed to take pictures ofhim on his own, only as part of a larger group.

Ultimately, Greenwood has been presented with the opportunity because of the World Cup. The bulk of the first-team squad is on holiday after the tournament in Russia and Mourinho has bolstered his numbers with the best young players. Still, it is an incredible achievement for Greenwood, who won't turn 17 until October, to be asked to train with the likes of Juan Mata and Anthony Martial this summer.

To put it into context, James Wilson, six years older and with three Premier League goals to his name, has been left at home.

The chances are that Greenwood will not feature that much against Club America, San Jose Earthquakes, AC Milan, Liverpool and Real Madrid this summer, if at all, but