Per Wheeler, Herrera "innocently invited a friend with close links to Celta Vigo to [training ground] Carrington" before United faced the Spanish side in the UEFA Europa League and consequently received a "dressing down" from manager Jose Mourinho.
The former Juventus man captained United during their 3-0 Champions League victory over Basel in midweek, but would depart the game early after suffering a hamstring injury in the first half.
The United boss said: "Luke Shaw is not injured anymore so is a question of form, is a question of option".
"[Ander] Herrera, [Marouane] Fellaini, [Michael] Carrick are waiting for a real chance to start the matches and they are ready so this is also our way of thinking". So for me, it's simple and objective that he's not playing this weekend.
Honestly we miss Pogba and we need him but we have good players.
"I don't know if it's the same one". I don't know that I just it is a muscular injury.
But it has emerged Pogba has instead been receiving treatment from a personal trainer.
Wayne Rooney will return to Old Trafford for the first time since leaving Manchester United.
The France global left Old Trafford on crutches and Mourinho is unsure about his absence beyond Sunday's Premier League clash with Everton.
"Sometimes in England the word "legend" comes too easy".
They say the Spain global invited a friend with close links to Celta Vigo to United's training ground shortly before United played the La Liga club in the Europa League semi-final.