Not for the first time this season, it was the teenage duo who carried Manchester United on their shoulders during that thrilling FA Cup victory over Liverpool at Old Trafford. Kobbie Mainoo, dancing through Jurgen Klopp’s midfield like Fred Astaire across a ballroom, was so impressive during that 4-3 win that England boss Gareth Southgate wasted no time promoting the 18-year-old to England’s first team squad just 48 hours later. Alejandro Garnacho, meanwhile, assisted Amad Diallo’s 121 minute decider and played a major role in goals one and two. A constant menace on either flank. While the pr…