The much-decorated Brazil captain has spoken glowingly to us about the young protege, expressing his belief that the Academy product can become a mainstay in the engine room for many years to come.
Mainoo, who scored his first senior goal at Old Trafford in Sunday's 2-2 draw with Liverpool, was asked by Carlos G. in the United States to describe the education he has received from lining up with the South American, as part of our latest Fans' Q&A.
His answer suggested much is to do with off-the-ball work, such an important part of operating at the highest level.