Welcome to the Premier League.
Burnley were 24 points ahead of the Black Cats when the Championship campaign finished just over three months or so ago, so the sensible prediction on Saturday would, you'd have thought, been a Clarets win.
But Sunderland's summer business, the morale-boosting thumping of West Ham and Burnley's heavy defeat at Tottenham led to suggestions the tables might have already turned.
Saturday's 2-0 defeat was something of a reality check for Sunderland, and one main takeaway was obvious - miss your chances at this level and you'll be punished.
Had Eliezer Mayenda swept home, as he should have done, after five minutes when Dan Ballard headed into the striker's path just six yards out, this could - likely would - have been very different.
The same can be said of Chemsdine Talbi's opportunity when he chipped just wide soon after, by no means as clear-cut as Mayenda's chance.
But as Burnley boss Scott Parker wrote in his programme notes as he reflected on his side's opening day defeat at Tottenham, "a clinical edge is required in this league".
His side took note. They had two shots on target against Sunderland and scored two goals, the first from captain Josh Cullen two minutes into the second half and the second two minutes from time when Jaidon Anthony latched on to Cullen's superb through-ball, rounded Robin Roefs and wrapped up the points.
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Trai Hume simplified matters.
"It's the details," he said.
"If you don't score your goal, you'll get punished for it.
"We've missed our couple of chances in the first half and we struggled to create in the second and they get two chances and score two goals. So that's the Premier League for you.
"If you don't score your goals then you get punished. That's the difference."
Chances were hard to come by in the second half for Sunderland and the biggest concern for Regis Le Bris should be his side's struggle after the break.
That said, this is a Burnley side that only conceded 16 goals last season, of course.
Enzo Le Fee made a difference from the bench and at least added some drive to a Sunderland side that was short of ideas.
It was interesting, though, that Le Bris brought Le Fee on in the position he was keen for him not to play last season, the left side of the attack. With Romaine Mundle still out, Sunderland are short of options on the left, but it's on the opposite flank that Le Bris is keen to strengthen if he can in the final week of the window.
"Enzo did well last season in this position [left side]," said Le Bris.
"I think when you have a midfielder, a creative midfielder in this situation, it could be efficient.
"The central corridor was really compact, so often it's interesting to start with wide areas, but you need to give the ball in the right timing.
"That wasn't really the case today, so it was tough to find spaces and time, but it's a good option for the future."
How soon in the future will Dan Ballard return to action? The sight of the centre-half hobbling off inside 10 minutes was a major worry for the Black Cats and, given Ballard missed 24 Championship games last season, perhaps goes a long way to explaining why Sunderland are still looking to sign one more centre-half ahead of next Monday's deadline.
Ballard was missed at Burnley and while Jenson Seelt has made huge forward strides over the summer, he's still inexperienced and a work in progress. He was a touch fortunate after going down softly in the build-up to a disallowed Lyle Foster goal in the first half on Saturday.
Le Bris will almost certainly shuffle his pack for Tuesday night's Carabao Cup second round tie against Huddersfield and hand starts to the likes of Le Fee, Patrick Roberts, Dan Neil, Arthur Masuake, Nordi Mukiele and Anthony Patterson.
Can any of the above players force their way into the side for next week's visit of Brentford, which already feels like a big game.
How Sunderland respond to setbacks and defeats will be a deciding factor in how this season plays out for the Black Cats. Tottenham, who finished 17th last season, which would be success for Sunderland this term, lost 22 of their 38 games.
Defeats aren't disastrous in the Premier League, but Saturday was still an opportunity spurned for Sunderland, and you can't pass up too many of those.
Equally, though, there can't be an over-reaction to every setback.
"Absolutely, because I think we played well, especially in the first half," said Le Bris.
"It means that we're still a work in progress. We need time, we need to be clinical in that league. Otherwise, we know the output and the outcome of the game.
"It's not a surprise now, it's just time to work
"You enjoy when you win, but you can't be too negative when you lose, I think we'll be balanced."