With a number of fringe first-team players on show, it was an opportunity for several Black Cats to stake their claim – with Arbenit Xhemajli, George Dobson and Jack Diamond all involved.
So who took that opportunity, and who still has work to do?
Scroll down and click through the pages as we dish out our player ratings:
1. Anthony Patterson
Little he could do about any of the three goals and made some smart stops as the game progressed - including one brave low save to keep out Joe Geldhart. 6 Photo: FRANK REID
2. Sam Wilding
Had the unenviable task of dealing with Leeds’ flowing forward line and could only watch as Greenwood ghosted past him for the opener. Came close to a leveller at the end of the first half, but then missed a crucial interception for the Whites’ third. 5 Photo: Morgan Harlow
3. Cieran Dunne
Asked to play as a wing-back, he was at times a useful outlet going forward but was caught out at the back on more than one occasion. 5 Photo: FRANK REID
4. Jake Hackett
His set-piece delivery was mixed and he failed to really assert himself on the game. Showed great determination to continue after some heavy challenges towards the end of the first half. 5 Photo: FRANK REID