Newcastle United Under-23s ended their pre-season campaign with a 3-1 defeat against their Barnsley counterparts at Oakwell Training Ground.
Barnsley's Sam Fielding opened the scoring with a powerful header before Oisín McEntee's unfortunate own goal doubled the home side's lead.
Elias Sørensen pulled a goal back for the Magpies with a terrific finish on the stroke of half-time before another own goal, this time resulting from Rosaire Longelo, sealed Barnsley's victory.
Neil Redfearn's youngsters headed into their final pre-season friendly of the summer in a confident mood following away victories against Hibernian's Development Squad and Rotherham United.
However, the Tykes took the lead inside 11 minutes as Fielding, Barnsley's skipper, rose highest from Alex Woolerton's corner and headed beyond goalkeeper Jake Turner - making his debut in between the sticks for the Magpies.
The home side doubled their advantage in the 23rd minute after Dani Pinollos' teasing cross from the left wing took an unfortunate flick off McEntee's boot, lifting the ball over Turner and dropping into the net.
United's first shot on target resulted in United halving the deficit, as Sørensen brilliantly controlled Owen Bailey's lofted free kick with his chest before the Danish forward cleverly lifted the ball beyond Walton.
In the second half, Newcastle brought on new signing Kyle Scott for the second half and the former Chelsea midfielder went close to making an immediate impact as the 21-year-old saw his strike crucially blocked after a neat combination of passes with United's Oliver Walters.
United's attacking threat was clearly evident after the restart, with Sørensen going narrowly close to adding his second goal of the match as the teenager's free kick, situated 30 yards from goal, curled inches past the left-hand post.
United's second-string continued their search for an equaliser as Luke Charman was sent on towards the latter stages of the contest and the Newcastle-born striker forced Walton into tipping a fierce strike over his crossbar.
But, despite dominating large spells of the second half, United were dealt another negative blow as Barnsley extended their advantage.
Following another dangerous cross into the United penalty area, Rosaire Longelo was unable to turn the ball away from danger and instead, diverted the ball into the right-hand corner.
Newcastle United Under-23s: Jake Turner (Dan Langley 61), Ryan Barrett (Luke Charman 61), Oliver Walters (Rosaire Longelo 61), Oisín McEntee (Jude Swailes 75), Lewis Cass, Kell Watts, Mo Sangare, Owen Bailey, Elias Sørensen, Tom Allan, Jack Young (Kyle Scott 46).