Phil Jones also had a nightmare at the back, which prompted some rather scathing comments from United legend Phil Neville on Match of the Day 2.
"They have got the best defensive record because they have the best goalkeeper in the world in David De Gea and [Nemanja] Matic out in front who protects them really well", said Neville.
Jose Mourinho is planning to offload Chris Smalling and Phil Jones in the summer as part of a major shake-up of Manchester United's defence, according to #The Mirror newspaper. Jones and Smalling didn't impress, and they were equally uncertain against Tottenham two weeks ago, when Harry Kane gave the duo a hard evening at Wembley.
Mourinho is not the only person skeptical over Smalling and Jones, with ex-United defender Phil Neville - the new England women's manager - having expressed his concerns over the partnership. Against Newcastle, did they make many mistakes? No. No, but they created a nervousness and a tension.
It hasn't gone unnoticed at United that their two biggest rivals, Liverpool and Manchester City, forked out £75m and £57m on centre-backs Virgil van Djik and Aymeric Laporte last month, and consequently Mourinho has told the United board that "they must start spending big on defenders".
"They were making decision that were odd".
Yet while Mourinho has decided his defence needs strengthening, United actually have the best goals-against record in the Premier League this season.
Jones and Smalling have been exposed as a partnership in recent weeks.
This season, Smalling has slowly become a regular following the injury suffered by Eric Bailly, who has been sidelined for the last three months.