Sunderland's unbeaten start to the new campaign ended with a 2-0 home defeat to Leeds United.
A goal in each half from Samuel Saiz and sub Stuart Dallas ensured the Elland Road outfit left Wearside with all three points.
Here's what we learned from the Championship encounter:
A game too far for unchanged side:
Sunderland boss Simon Grayson named an unchanged starting line-up for the fourth Championship game in a row.
It has been a hectic schedule for Sunderland against strong opposition - with a Carabao Cup win sandwiched in between.
There were four changes for that cup win but in the main the same team has been playing.
It looked to have finally taken its toll against Leeds, Sunderland were bright for 20 minutes but once Leeds scored they appeared leggy and it was no surprise to see early subs.
Most would have kept faith with the same team, with perhaps Wahbi Khazri the only contender to have started, though that would have meant George Honeyman or Aiden McGeady being
dropped - two men in form prior to kick-off.
A difficult balance to strike for Grayson but expect changes for Carlisle United as Sunderland look to get back to winning ways.
Defensive frailties exposed:
Football can be a simple game at times. Early on, Leeds spotted that Brendan Galloway was having an uncomfortable evening and was the weak link in the defence.
And they exploited it at will. Ezgjan Alioski was superb, constantly probing and pressing down Sunderland's left. Galloway endured a torrid afternoon. No surprise to see him subbed.
The opening goal came down that side, with Samuel Saiz gifted too much space inside the box with nobody tracking his run.
Sunderland should have been in front by that stage but their defensive frailties cost them.
Didier Ndong impresses:
The star of the Sunderland show though was Didier Ndong in central midfield. He was excellent throughout.
His passing can still frustrate but his willingness to want the ball and get Sunderland moving always catches the eye. Fond of a tackle too and intercepting play.
The demanding schedule didn't seem to affect Ndong, who can run all day.
Bryan Oviedo return will be like a new signing:
It didn't take a trained observer to realise Galloway struggled at left-back against Leeds United.
He has had a mixed start to life on Wearside with flashes of promise coupled with shaky performances were he has been exposed at the back.
The return of Oviedo can't come quickly enough for Sunderland, a Premier League defender, his return from a calf injury will be like a new signing. Someone Galloway can learn from.
No need to panic after first defeat:
Overall, four games in and Sunderland have enjoyed a solid start to life in the second tier.
Draws against Derby County and Sheffield Wednesday, victory over Norwich City and a defeat to Leeds United.
Most supporters would have been satisfied with five points from the opening four games.
Defeat to Leeds was disappointing and a timely reminder of the harsh reality of the Championship but there is still plenty to be optimistic about.
Sunderland do, though, need more bodies in before the window closes.
Defeat reinforced need for strength in depth:
Grayson knows it, the fans know and surely Ellis Short must know it. Sunderland need far more strength in depth if they are to cope with the gruelling schedule of the Championship.
As the manager pointed out, the club has had a demanding start - tougher than most . It has exposed the lack of depth in the squad.
The players have been in form so Grayson was reluctant to change the side but in truth his options were limited anyway.
The return of Oviedo, Rodwell, Watmore and McNair will help boost numbers but Sunderland are still a central defender short, another wide option plus at least one striker - and that's before any other possible departures.
Big two weeks ahead.