The Red Devils make the trip to League One side Shrewsbury Town in the FA Cup fifth round on Monday night as Van Gaal’s men look to end a two-game losing run in all competitions.
United were beaten 2-1 by FC Midtjylland in the first leg of their Europa League last-32 tie on Thursday just days after the 20-time English champions suffered a 2-1 loss to Premier League strugglers Sunderland.
Van Gaal’s predecessor Moyes, who was axed by the Red Devils in April 2014 less than 10 months after taking over from Sir Alex Ferguson, believes United shouldn’t become a sacking club.
“I don’t think Man Utd should become a sacking club,” Moyes told BBC Sport.
“I was disappointed when I lost my job after 10 months. Man Utd have always stood for much greater things than sacking their managers regularly. So I don’t think they should.”
Van Gaal led United back into the Champions League in his first season in charge at Old Trafford after replacing Moyes.
However, the Red Devils are in fifth place and six points behind Manchester City, who occupy the final Champions League qualifying spot.
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