What a difference a week makes.
This time last week Sunderland fans, players and coaching staff were rejoicing following a superb 4-0 win over relegation rivals Crystal Palace.
Fast forward seven days and it was the Black Cats on the end of a humiliating defeat, Southampton putting Sunderland to the sword.
Here's what we learned:
Sunderland's mental fragility exposed again:
On the back of the 4-0 thrashing of Crystal Palace, confidence levels couldn't have been any higher going into the game.
And in the opening 25 minutes, Sunderland played some of their best football of the season at the Stadium of Light - yet crucially failed to capitalise on their pressure and paid the price.
That confidence visibly drained as soon as they fell behind and the Black Cats never recovered.
Saints trio dominate Sunderland:
Sunderland never got to grips with the threat of Ryan Bertrand down the left, the movement of £17million man Manolo Gabbiadini or Oriol Romeu, who dominated midfield.
Gabbiadini's first goal shouldn't have counted but he showed his class with his second, with Sunderland's dismal marking helping him along the way.
It was inevitable Gabbiadini was going to end up on the scoresheet given his namesake's legendary status at the club.
Romeu was outstanding in central midfield but Sunderland made it too easy for the Saints.
Sunderland's attack laboured and predictable:
Against Palace, Sunderland's attacking play was purposeful and clinical. Fast forward a week and Jermain Defoe was once again isolated leading the Sunderland attack.
Adnan Januzaj, who had showed signs he had turned a corner against Palace, looked in the mood in the opening stages, working hard and linking well.
But as soon as Sunderland fell behind, the wheels came off in dramatic fashion. The Black Cats devoid of ideas, creativity and willing runners to support Defoe.
As Moyes said post-match, the more attackers they put on the pitch the worse they were.
Lamine Kone goes from hero to zero:
Kone's return from the Africa Cup of Nations coincided with Sunderland's recent - albeit brief - upturn in fortunes.
Outstanding against Spurs and Crystal Palace, Kone was poor against Southampton. Gabbiadini lost him and O'Shea for both of his goals.
Kone looked out of sorts all afternoon as Southampton ran riot.
Can't keep relying on rivals getting beat:
After recording the worst ever start to a Premier League campaign, it is incredible Sunderland are even still in touch at the bottom.
But they are and Sunderland remain a win away from fourth-bottom thanks to defeats for Hull City and Crystal Palace.
Sunderland, though, cannot keep relying on the results of others.
This was a golden opportunity to move out of the relegation zone. And it was squandered in spectacular style.
Darron Gibson shows his intent.
His first pass was astray but Gibson composed himself quickly and was helping make Sunderland tick in the opening 25 minutes; composed and calm in possession, keeping the play moving.
Gibson has an eye for a pass and while they didn't always come off, at least he was trying to be positive.
He visibly tired after the break in only his fourth appearance of the season but his performance first half was one of very few bright spots.