The forward and his sibling died in a car crash while on holiday in Spain.
Figures from across the footballing world, including past and present United players, have paid tribute to the 28-year-old, who also played for Portugal, FC Porto and Wolverhampton Wanderers, among others.
Captain Bruno Fernandes shared an image of himself with the striker on his Instagram page, alongside the following message:
“Friend, colleague, and companion in a thousand battles. It’s hard to understand how it’s possible for someone to leave so soon.
“May you and your brother find the peace you need to look after those who lost you so suddenly and so soon. My condolences to all your family.”