United dropped points once again on Saturday afternoon after Che Adams cancelled out Jadon Sancho's first half opener.
It's the third time in three games that Ralf Rangnick's side have let a 1-0 lead slip after the break and Neville pinpointed exactly what they were doing wrong.
He explained on Twitter: "Breaking every rule in the book here United on how to chase a goal! Don’t give fouls away, don’t give the ball away, don’t force it, don’t lose your discipline and chase the ref etc etc!"
Breaking every rule in the book here United on how to chase a goal! Don’t give fouls away , don’t give the ball away, don’t force it , don’t lose your discipline and chase the ref etc etc ! Probably score now 😂— Gary Neville (@GNev2) February 12, 2022
Sancho scored his first Premier League goal at Old Trafford in the 21st minute after finishing off a slick counter attack.
Marcus Rashford was unleashed down the left and he fired a cross in for Sancho to tap home with ease.
United had their chances to pull ahead but allowed Southampton to grow into the game, with Stuart Armstrong testing David de Gea just before half-time.
Adams made the home side pay in the 48th effort when his delicate finish bounced in off the post.
Armando Broja gave Harry Maguire a tough game and tested de Gea on a few occasions, as did Armstrong once again.
Maguire had United's best chances of the game, including a header in the 92nd minute which was kept out by a diving Fraser Forster.
United players were unhappy with a number of fouls the Saints players played and that frustration likely boiled over into their play.
Southampton manager Ralph Hasenhuttl claimed at full-time that it's 'not a big secret' that United find it hard to track their runners.
He said: "It is not a big secret that when they lose the ball that the reverse gears are not the best from everybody.
"Then you have the chance to create something and we did.
Ché Adams levels it up for the Saints! 👊— Football on BT Sport (@btsportfootball) February 12, 2022
Southampton have had some great chances in this game, and they finally score ⚽️
A well-taken finish from the forward 🎯 pic.twitter.com/U1BLs77Vg0
"The pressing for them was good in the beginning, but they aren’t used to doing it for more than 30 or 40 minutes, we came into the game after that."
United are now fifth in the Premier League table after West Ham United's 2-2 draw with Leicester City on Sunday.
They can move into the top four should they beat Brighton & Hove Albion on Tuesday.
Featured Image Credit: Sky Sports & Alamy
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