The pace of change on Wearside and Teesside has been dramatic since the sides last met in April.
The two meet on Sunday lunchtime (12.15pm kick-off) separated by 13 points and 14 places in the Championship table.
We caught up with Jonathon Taylor from the Teesside Gazette to survey the scene.
The two sides took rather different approaches in the transfer market this summer...
PHIL SMITH: Most actually felt Sunderland had a decent summer, in very relative terms.
The scale of investment in the squad, given the money recouped from the selling the likes of Jordan Pickford, was a massive disappointment and, for many fans, highlighted a lack of ambition.
What Simon Grayson did with that budget was reasonable, the likes of Aiden McGeady and Lewis Grabban two of the better performers. The biggest problem was fitting them into a cohesive unit, something he never came close to achieving.
JONATHAN TAYLOR: The overwhelming emotion on Teesside was regret when Boro’s Premier League fate was sealed at the end of last season.
There was a niggling feeling that the club just didn’t ‘have a go’, and that regret, from top to bottom, fuelled a huge rebuilding job over the summer.
Ten new players arrived, along with a new manager and coaching set-up, and Boro seemed to learn from mistakes of the past.
There were no ‘projects’ or unknown quantities recruited over the summer. In came tried and tested options ready for the Championship slog.
Boro did some smart work in the window to offload those who didn’t cut it last season, recouping a significant sum, which was then reinvested.
More than £40m was spent – with chairman Steve Gibson backing up his much-quoted desire to ‘smash the league’.
Garry Monk was being talked about a lot at both clubs...
PS: Garry Monk was certainly considered and one of Sunderland’s top choices, though I do think Derek McInnes was the one they really wanted.
I don’t think Monk was ever that likely to come to Wearside. Who doesn’t want £30million to spend on strikers and have a chairman who you know will back you to the hilt?
JT: Steve Agnew was in charge for the relegation dead-rubber with Sunderland at the back end of last season, and there is still some mystery over whether he remains at the club or not. He’s certainly not been seen around the club since the summer, but no official clarification has been forthcoming.
Garry Monk was seen as the managerial front-runner as soon as he resigned from Leeds. While Boro took their time to assess all of their options, it always looked inevitable that the former Swansea player and manager would be heading to Teesside.
After the last few years, the next Boro boss was always going to be somebody with a more attacking ideology, who likes to play attractive football and can bring a swagger back to the club.
So Monk seemed the obvious shout – and, after a sticky start, things appear to be picking up.
Things are looking up for Boro...
JT: If you asked a couple of weeks ago, it would have been a disappointing start with Boro 13th and off the pace.
But since then – aided by a consistency in terms of shape and personnel – they have picked up away wins at Reading and Hull, putting in arguably their two most convincing performances of the season.
All of a sudden, Boro are within touching distance of the top six – and will now be looking for a big couple of months to claw back the gap between themselves and Wolves at the summit.
So what’s the mood like going into this game?
PS: The pressure was really starting to build on Simon Grayson, so, in a sense, it perhaps lifts a weight that it will be Robbie Stockdale and Billy McKinlay in charge on Sunday.
With so much talk about the next manager, and a strong sense that it will have huge repercussions for the future of the club, the game itself has perhaps taken a bit of a back seat, which might work in the squad’s favour.
JT: Optimism and excitement, you’d have to say.
Things can change very quickly in the Championship, and back-to-back away wins have galvanised the club, lifted the players and reenergised the fans.
All of a sudden, with a supremely-talented squad at his disposal, Monk has got some momentum – and now Boro’s mettle will be tested with games against Sunderland and Leeds in their next two matches.
But, given what’s been going on at Sunderland, and their desperate form of late, Boro fans will be expecting three points on Sunday.
What’s the key for both teams?
PS: Generally speaking, though there have been a couple of absolutely shocking performances, Sunderland have looked a little better on the road and they might be quite happy to play a side that will look to have most of the ball.
Duncan Watmore’s pace and Aiden McGeady’s creativity give them some threat on the counter and that’s how you would expect them to play.
As is always the case when a manager goes, I think the first thing will be to try to instill some organisation and discipline.
JT: Get the first goal. It sounds simple, but before Boro’s form turned around at Reading, they conceded the first goal in eight of their 13 league matches.
They were accused of being slow-starters, and certainly at home, the team tended to give the opposition time to settle and encouragement that there were points up for grabs.
When Boro score first, they look to settle – that much was evident at Reading and Hull – but the team are prone to mistakes and can look unsettled if stubborn opponents sit deep, frustrate and then pounce on the counter-attack.
If Boro start quickly and force an early breakthrough, Sunderland could be in for a long afternoon.
But if the visitors can contain and grab the first goal... you never know!