A third defeat out of five, even if it is only pre-season, inevitably sparks a louder encore of calls for further investment in Sunderland’s playing squad.
In fairness, Sunderland’s performance at the Keepmoat Stadium was much brighter than the leggy, jet-lag ridden displays they produced during their three encounters in North America, with a combination of defensive errors and poor finishing proving fatal.
But it is impossible to dispute the need for another couple of attack-minded recruits before the transfer window shuts, even if no-one arrives in time for the Premier League opener at Leicester City in less than a fortnight. Much work is clearly still needed.
The understandable worry heading into the new season is who will solve Sunderland’s age-old problems in front of goal.
At least though, Sunderland appear to have addressed one deficiency which feels like it has been “age-old” – the one about adding some pace in the final third to the Black Cats’ ranks.
On the evidence of his Sunderland bow (yes, debuts are always unreliable, to add to the unreliability of pre-season) Jeremain Lens is going to become a real fan favourite on Wearside.
Lens was the star of the show in South Yorkshire – quick, strong, capable of beating a man, getting to the by-line, delivering a cross and yes, even boasting an eye for goal.
At times during the second half when Lens seemed intent on dragging Sunderland back into the contest by himself, it was no surprise that his team-mates were patting him on the back.
The £8million man stole the limelight from fellow new boy Younes Kaboul, who was content to stroll through the second half, as he eases his way back into competitive action.
By the time Kaboul entered the fray at the interval though, Sunderland – who had seen Patrick van Aanholt hit his own post in the opening stages – were trailing after falling behind on the quarter-hour mark.
Harry Forrester’s looped cross from the right flank found Cedric Evina unmarked at the back stick, who had all the time in the world to cushion a half-volley beyond Costel Pantilimon.
Dick Advocaat then tinkered with his 4-2-3-1 system, with Jermain Defoe moving into a more familiar central position, and Lens and Adam Johnson taking the two spots out wide.
It sparked an improvement, with Johnson going close to levelling in the 31st minute after he beat the offside trap to Jack Rodwell’s lovely arched ball over the top, to leave himself with a clear run on goal.
But after bringing the ball under control, Johnson could only scuff a shot which deflected into the arms of Doncaster keeper Thorsten Stuckmann.
Lens continued to be Doncaster’s chief tormentor though; going close seven minutes before the interval when he cut inside off the left, went past two defenders and a hit a low shot from the edge of the box which deflected just beyond the far post.
Sunderland went even closer moments later when Lens picked out the run of Fletcher, who just managed to keep it away from Stuckmann despite a heavy first touch with his chest.
Fletcher laid it back to Defoe, just inside the area, but his low shot was deflected inches over the top by centre-half Rob Jones.
Kaboul was one of four substitutes introduced at the interval, with one of those replacements - Danny Graham - going close to a 57th minute leveller.
Lens pressurised Doncaster right-back Luke McCullough into a loose touch and it fell to Graham, just inside the area, who hit a first-time shot that was gathered well low to his left by Stuckmann.
But it was the hosts who doubled their advantage just after the hour mark when Jack Rodwell was needlessly sloppy in clearing a low pull-back from the left.
Rodwell thrashed the ball into the back of Harry Middleton and it rebounded invitingly into the path of Harry Forrester, who sent a half-volley beyond Pantilimon into the far corner.
Johnson forced Stuckmann into a save in response, the Doncaster keeper tipping over a shot after the winger cut inside off the right.
Lens then almost produced a stunning individual strike; holding off two Doncaster players 25 yards out before unleashing a right-foot thunderbolt that Stuckmann managed to tip over the bar.
He was the undoubted shining light for Sunderland, albeit Emanuele Giaccherini skied a great chance to pull one back late on.
But over the next few weeks, Sunderland are going to need some more of that “quality” around Lens, which Advocaat had identified at the end of last season.
Doncaster: Stuckmann (Marosi 82), McCullough, Taylor-Sinclair, Butler, Jones, Evina (McKay 86), Wellens (Carberry 86), Coppinger (Mandeville 83), Middleton (Lindley 86), Keegan (Whitehouse 67), Forrester (Pugh 83).
Sunderland: Pantilimon, Jones (Matthews 63), O’Shea (Kaboul 46), Coates (Beadling 63), van Aanholt, Cattermole (Larsson 46), Rodwell (Bridcutt 71), Johnson (Buckley 82), Lens (Watmore 82), Defoe (Giaccherini 46), Fletcher (Graham 46). Subs not used: Pickford, Mannone.