United put in one of the worst performances in their recent history, conceding three to go in 3-1 down at the break at the Amex.
Paul Pogba netted a late penalty to make the 3-2 scoreline respectable but it merely papered over the cracks of what could be a club in crisis.
United failed to bring in their top transfer targets this summer, leaving them with a wafer-thin defence which was brutally exposed on the south coast.
There are suggestions their record signing Paul Pogba has had a row with boss Jose Mourinho and he could even leave before the end of the month. Barcelona are interested in signing him before the August 31 deadline but know they may have to wait given United can’t sign a replacement.
TV cameras showed an angry-looking Woodward slumped back into his chair at the final whistle as he pursed his lips. The Old Trafford chief was then seen leaving his seat to rush into the dressing room in the aftermath.
He stayed there five minutes before leaving and not waiting for Mourinho, who was doing press interviews at the time, while typing a message out on his phone.
Manchester Evening News reporter Ciaran Kelly tweeted: “Ed Woodward, alone, has just popped into the United dressing room #mufc
“Ed Woodward was in the away dressing room around five minutes. Left typing a message into his phone. Appears to have missed Jose Mourinho who was doing flash interviews at the time. Didn’t wait for him #mufc”
When the Woodward images were early broadcast on Sky Sports, commentator Martin Tyler said: “Manchester United have some sorting out to do with the personnel they have.
“He was the man in charge of bringing players in before the window was shut.
“You know from Jose Mourinho he didn’t get what he wanted and you could see that today.”
Appearing on Sky Sports alongside Tyler, United legend Gary Neville added: “Manchester United were poor on the ball and poor off the ball.
“They weren’t good enough in attack but the back four, especially in the first half, melted.
“You can’t melt away from home in the Premier League. You have to stand up strong.
“Deep down Jose Mourinho will know he wanted men of authority and leadership at the centre of his defence and he doesn’t feel he’s got them.”
Mourinho had earlier refused to answer one question from Sky Sports as he got tetchy after the shock defeat.
Mourinho was asked by a Sky Sports reporter after the final whistle if the thought United suffered from poor individual performances.
But the question didn’t go down well with the United boss.
“When I talk about individual performances, and sometimes when I’m critical with players, you just don’t accept it,” he snapped back.
“The press, the pundits, are always very critical of me when I go in that direction so please don’t ask me to go in this direction because it’s not good for me.
“I will be very, very happy to analyse my players’ performances when the performances are very good.
“It’s a great thing for me to come in front of the cameras to come and say players a, b and c had fantastic performances and were amazing for me.
“When I can’t do that, don’t push me to the other side as I don’t want to go to that side.”