Junee ensured there would be no more late heroics from Young to bring up a crucial win at Laurie Daley Oval on Saturday.
The Cherrypickers scored two late tries to force a draw with Temora last week, but fell two points short this time around.
Six points was the biggest margin all day in the see-sawing clash but the Diesels just had enough to run out 22-20 winners.
The loss sees Young slip behind the Diesels on the Group Nine ladder and into seventh place.
They've won just once plus had a draw with the Dragons.
Cherrypickers coach Roy Jewitt said his side were shocking, especially after conceding so many points right after scoring themselves.
"Schoolboy errors just kept them in the game," Jewitt said
"We should have put them away by half-time but they kept going and we were ordinary.
"Our kicking game was very poor and I don't know what is going on."
Young got off to a perfect start when their kick off found touch and they scored through Numiasasulu Tema in the first attacking set of the game but two tries from Daniel Foley saw the two teams head into half-time locked at 10-all.
The two teams went try-for-try in the second half as both converted on each other's mistakes before Dakota Ruta scored the what would be the match winner from dummy half with seven minutes remaining.
Jewitt made plenty of positional changes with the arrival of the Fijian international.
Jesse Corcoran looked sharp in his move to hooker, and the Englishman was pleased with Komaisavou's first half but admitted there is plenty of work to do ahead of a tough next month.
They face Southcity, Tumut and Albury, who are all in the top four, in the next three weeks.
Jewitt is looking for some swift improvement.
"We just get away from what we are training to do and it shows," he said.
"We still have a lot of work to do.
"We've got some tough footy ahead but hopefully it will bring out the best in us."
After just one win from the first four rounds, Junee captain-coach Trent Schubach was relieved to win. "We really needed it," he said.