United started the match with two wins from their opening two games in the group but then found themselves 1-0 down in the 12th minute when Demba Ba inexplicably ran unopposed from inside his own half and clear of Nemanja Matic to finish coolly past Dean Henderson.
Edin Visca doubled Basaksehir’s lead before Anthony Martial pulled a goal back but United were unable to find an equaliser and suffered their first defeat in Europe.
When asked for his opinion on United’s display and Ba’s goal on Twitter, Neville needed just one word: “Embarrassing.”
Neville’s unhappiness followed similarly scathing assessments by his former United team-mates Paul Scholes and Rio Ferdinand.
When asked to explain Ba’s goal, Scholes said: “Surely you always have someone back on the halfway line, they’re pointing at Matic. You’re always goalside, it’s like Under 10’s football.
“You can understand if it’s last-minute but it’s the first ten minutes, it’s embarrassing.
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“They’ve struggled with them attacking wise, they’ve gone with one holding player today. Defensively they’re all over the place.
“The defenders have to be better, forward play could be better as well. Defensively they’ve got to take responsibility, you have to defend 1v1 sometimes when you’re at Manchester United they seem incapable of doing it.”
While Ferdinand added: “Where is the organisation in this team? You wouldn’t see this on Hackney Marshes.
“I hope Ole is in there telling them ‘you are embarrassing yourself and me’.
“Those players need a rocket because the way they’re performing at the moment – the inconsistency, how they are allowing people to run off them, I don’t see any intensity at all.
“I don’t see them ruffing any feathers on a consistent basis. If you want to be a top club you need that week in and week out and those demands have to be put on everyone.”