As Tom Brady walked onto the Old Trafford field to greet Cristiano Ronaldo after the Manchester United striker's hat-trick in Saturday’s 3-2 Premier League win over Tottenham Hotspur there was a knowing smile on his face.

What would surely have most impressed former NFL great Brady, who retired last month aged 44, was not the stunning 25m opener nor the well-placed header to win the match nine minutes from time but the look of determination, bordering on anger, that the 37-year-old Ronaldo had throughout the game.

Brady was not like that. He kept his emotions well hidden for most of his Hall of Fame career as a quarterback for the New England Patriots and latterly the Tampa Bay Buccaneers, before retiring with a record seven Super Bowl triumphs...