The Black Cats headed into Tuesday night's home clash with travel-sick QPR at the Stadium of Light on the back of a four-game unbeaten run in all competitions, with head coach Gus Poyet believing they had turned a corner.
However, in the space of 46 soul-destroying minutes, they capitulated in alarming style to a side which had failed to collect anything at all from their previous 11 away games, and even a frenzied second-half fightback which did little to placate Poyet could not prevent them from slipping to a damaging 2-0 defeat.
The Uruguayan later insisted something fundamental had to change if they are going to shed their one step forward, two steps back approach, and midfielder Larsson mirrored his view.
The Sweden international said: "You can never take anything for granted in this game and we've experienced that many times before.
"I think the most frustrating thing is we felt like we were on the up, we felt like we were moving in the right direction.
"It's a game we shouldn't have lost, but we did, so we can only blame ourselves
It was down to us players on the pitch and we didn't do enough.
"I've been here long enough to know that we tend to do these things at times, and we need to figure out why because it shouldn't keep happening."
The omens could hardly have been any stronger in Sunderland's favour before kick-off with managerless Rangers arriving without a host of key players, including 13-goal top scorer Charlie Austin, through injury.
But with chairman Tony Fernandes having taken to his Twitter account to reveal he was close to landing a replacement for Harry Redknapp, it was they who took the game by the scruff of the neck, exploiting the lack of protection afforded to left-back Patrick van Aanholt by Poyet's 4-1-3-2 formation in clinical fashion.
It was down that wing that midfielder Matt Phillips produced the crosses from which Leroy Fer headed the visitors into the lead before he repeated the feat to set up Bobby Zamora's expert finish, and although Rob Green had to pull off fine saves to deny Connor Wickham and Jermain Defoe, that proved enough.
Afterwards, Poyet could not hide his frustration at his players abandoning his methods to respond to the home crowd's pleas for a response in direct fashion.
He said pointedly: "If the second half is what they want - and they have been asking for it for a while - then they need to be a little bit more proud of the team because that is what they are asking."
If Poyet cut a glum figure as he surveyed the wreckage of yet another false start, opposite number Chris Ramsey wore a broad smile.
QPR's head of player development left Wearside knowing he had achieved what Redknapp had been unable to do since Rangers' return to the top flight and claim all three points away from Loftus Road in what could prove to be his final game in temporary charge.
Michael Laudrup had been installed as the bookmakers' new favourite to succeed Redknapp hours before kick-off following Fernandes' revelation, and Ramsey was a picture of modesty as he prepared for a return to the ranks.
"There's a lot put on that managers come in and wave a magic wand and everything is great
If you look at the players that we have got there, some of the players that came in - I think we had six changes - they all came in and did well," he said.
"The players at the weekend all did well as well
We were unfortunate not to at least get a point at the weekend, so I wouldn't say it's anything fantastic or magic that I did that made the difference.
"I have always said it before, win draw or lose, I have always said it's really down to the players' intrinsic motivation, whether they are prepared to put their bodies on the line like they did, and obviously play to their potential."
Source : PA
Source: PA