After just 50 minutes of the Premier League clash at Old Trafford, United were trailing by five goals after goals from Mohamed Salah, Naby Keita and Diogo Jota.
“Sometimes the result is not the one we fight for. Sometimes the score is not the one we want. And this is on us, only on us, because there’s no one else to blame,” the Portugal star wrote in an Instagram post.
“Our fans were, once again, amazing in their constant support. They deserve better than this, much better, and it’s up to us to deliver.
“The time is now!”
United are now seventh in the Premier League and eight points behind leaders Chelsea.
They face Tottenham next week, followed by an away game against Atalanta in the Champions League on November 2.